Within Lukumi/Santeria, there is a system of divination known as Obi Obata.  It uses a quartered kola nut used to acquire an answer from the ancestors upon consulting with the ancestors.  In the New World, the kola nut was not to be found, so the coconut was used in replace of it.  Some used the whole coconut, quartered and dropped upon the ground and read in accordance to how it fell, and others, such as in Palo, used the shell itself.  Later on, others began using the cowrie shell, a variation of a sixteen cowrie (merindillogun) used by babalochas when consulting the Orisha.

The four-shell system of cowrie divination is to be used exclusively for communication with the ancestors.  While known for being considerably accurate in proper interpretation, it doesn't allow for all of the dynamics found in the sixteen shell form that is used only by initates of Lukumi and only for consultation of the Orisha.  The four-shell version of Obi Obata can very well be used by non-initiates.  It never was made anything particularly secret, and families in Cuba used it before it hit the States post Cuban Revolution.

Obi is a yes-no system, BUT offers indepth anaylsis into it.  It's not just a yes or a no, but a "why" to the answer may likewise be given.  Once adjusted to the system, you will find that your answers go far beyond a mere no, but allowing for the specifics as to why or why not.

You need four shells.   With the shells, you need to "open" their mouths-- that is, file a hole in the convex side of the shell, as within the three shown turned up in this photo.

After you have opened their mouths, which takes a little patience, the first thing you need to do is to cool Obi by dropping the shells in cool, clear water.  You will need to libate Obi in such a way prior to any readings.  I had a oyster shell that I filled with water and set Obi in before the readings.  This keeps Obi's mouth hydrated and ready to talk.

Keep Obi upon your ancestor altar when not in use.  This will acclimate Obi to the energies of your particular ancestors and thus, they will be able to better communicate through them.  It may be wise to set them there first and then put to memory the divination process-- which while simple, is very accurate.  Out of several hundred readings through Obi, I can attest that Obi has never once lied to me in conveying answers from the ancestors.

After calling your ancestors, through the water, to your altar, and having greeted them-- you may wish to ask for their consultation.  There may be questions that you have of which you can find no resolve.  Pick up Obi from the water, hold it up to your head and ask Obi to give you your council through the ancestors.  Then ask the ancestors your question.   Drop Obi upon the altar- I would recommend a bowl or tray with a flat bottom to catch them, so that they do not fly everywhere upon hitting your altar.  Now interpret.

The open mouth up is the "light side" of Obi.  This is the side that you opened up from the convex side of the shell.  The mouth down, which is the natural opening up, is the "dark side" of Obi.

Here are your five initial interpretations:

• Alafia: 4 mouth-up cowries
  Blessings! A “Yes” to whatever you asked about — and you may get even more than you requested or it will come sooner than you hoped. Alafia means "peace." It represents all of the light that is available and able to assist you. It is "Yes" with a blessing of peace.   Although this is a very positive answer, it still requires one more throw of the cowries if you want to see exactly how stable and long-term this "yes" might be.
• Etawa: 3 mouth-up and 1 mouth-down cowries
  A "Maybe" answer. Etawa is an unstable response.  One has turned against three others, therefore while three say yes, there is an element of discord in the answer.  If you're going for a quick answer, Etawa would be a "yes"-- however, it's not stable enough to offer you a true satisfaction for that which you seek.  Like Alafia, when we get Etawa, we are advised to make another throw to get specifics.

• Ejife: 2 mouth-up and 2 mouth-down;
  This is an absolute “Yes” -- the perfect affirmative answer because it shows balance between light and dark.  Ejife says "without a doubt!", therefore do not ask the same question again.  Once you have this perfect yes, then there is no further need for interpretation or a re-toss of the shells. 
• Okanran: 1 mouth-up and 3 mouth-down
  “No.” What you asked won’t happen. Okanran is a firm no. Three have teamed up against one.  The level of contraction or opposition indicates much work is needed before the blessings in question could come to fruition. 
• Oyekun: 4 mouth-down cowries
  This is a very strong “No,” and it furthermore indicates that you may need serious spiritual cleansing or a total restart in your life on these conditions in order to clear away the negativity that surrounds this issue in your life. Oyekun represents total darkness and the spirits of the dead can speak through this answer. There is an elusive element to the situation, or the spirits may be asking for something. If you get Oyekun, you should wash out Obi's mouth by soaking it in some water and then taking the water to pour outside.  Upon returning inside, you should immediately ask other questions as to what is going wrong in this particular element of your life and seek solutions to immediately rectify it before it is "too late".

When you read Alafia or Etawa, you should throw again.  Alafia and Etawa, while meaning a "yes" in the immediate future, does not show whats later on down the road.  Therefore, you should make one more throw to determine how it will end after the blessings have subsided, or that one shell that turned against the other three fares out.

After Alafia or Etawa, you get another Alafia, Etawa or Ejife, then this means the positive fruitition of your question will carry on beyond the immediate future.  If Okanran or Oyekun, the positive affirmation of Alafia or Etawa will soon fade out-- so be on your guard.  It's "all good" now, but tomorrow it may not be.  That is what the second throw may show us.  More specifically:

• Alafia + Alafia: Yes. Blessings upon blessing, but be careful-- you might get drunk from the goodness floating around, and getting upon that high horse because it all seems so fantastic might end up as a fall later on.  Stay sober while appreciate those blessings.
• Alafia + Etawa:  Yes.  This indicates a time of peace, contemplation, rest and planning before a test or struggle. It advises clear-headedness and emotional coolness if victory is desired in the coming difficult situation.
• Alafia + Ejife: Yes.  This is a good omen that combines cool headedness and balance. It implies a "what will be, will be" attitude, and "what will be" is certainly good.
• Alafia + Okanran:  No.  This implies that no matter how much serenity and planning are represented by Alafia, Okana will throw a wrench into the works with one tiny unforseen factor. Largely negative, implying great caution, or abandonment of the activity in question to another time. 
• Alafia + Oyekun:  No.   Alafia-Oyekun can best be described as having just won the lottery, only to step off your porch to fall and break your neck.  It's the illusion of perfection when danger is right around the corner.  With Alafia-Oyekun, do not trust this moment of peace.  Use it, instead, to take cover and take counsel with those you trust, to minimize the lasting troubles.

• Etawa + Alafia:  Yes.  This implies a peaceful, satisfing situation that can only come about after hard work and perhaps competition and struggles. You must earn your reward.
• Etawa + Etawa:  Yes, with lots of struggle.  As the name of Odu implies this is a struggle after struggle. This is a situation of unrelenting effort before the desired goal is achieved. Any slacking means probable failure. In a lesser sense it can mean that nothing goes right no matter what you do.
• Etawa + Ejife:  Yes.  This represents struggle or effort leading to perfect balance and successful outcome.
• Etawa + Okanran:  No.  No matter how hard we work, our plans are fouled by one little event or element. This can mean frustration and failure after hard work or, in a more minor mode, working for perfection is getting mediocrity.
• Etawa + Oyekun:  No. The presence of Oyekun makes this black as a ace of spades. We struggle and struggle only to meet inevitable deafeat. Our own energy is even used against us to our undoing. Find an honerable way to retreat - or just duck and cover from the inevitable fallout.

Once you have completed receiving council from your ancestors, cool Obi off by putting the shells back into the water and continue on with service to the spirits.  Obi divination should not be taken lightly.  Answers given to you by the spirits may and should be recorded in a book for further speculation.  The questions you make should be fairly specific, too, when possible.  The rule, as within all divination:  Be careful in what you ask, you may not like the answer.

Treat your ancestors well and Obi with respect, and you'll find intuition increasing to expand upon the answers received and they will shed light on solutions of any problems that may come your way.