Along with the coconut milk and the green Key Ingredient, the bone is used to make a sleeping potion for the giant shark (Booga) that menaces the island. Get a grass skirt from the bay before bringing the ingredients to the medicine man.
(see related questions)
it is under the big tooth
The bone is down in the underground ruins. You will find it at the bottom of the hole with spikes on its sides, just left of the statue with the giant centipede on it.
The bone is in a tunnel deep in the underground ruins. You will find it when moving left from the door with symbols on it. (see related question)
You have to go into the ancient ruins and then get past the secret code door. The bone is at the bottom of the area with spikes on either side, just past the giant shark statue with the giant catapillar.
In the Temple
you have to have a beast bone, the free organic coconut milk and the key ingredient, which is found in the ancient ruins
The ingredients on Shark Tooth Island are1) coconut milk (from the island vendor on Main Street)2) a dinosaur bone found in the old ruins3) the green "key ingredient" also in the ruins at the far left of the cavesYou also have to have a grass skirt to convince the native man to make the potion for you. He is found at the top of the "tree" next to the ruins..
The green "key ingredient" on Shark Tooth Island is part of the potion to put the giant shark (Booga) to sleep. It is down in the underground ruins, along with another ingredient, the creature bone. Open the underground door and go left to find the bone and then the key ingredient. (You already have the third ingredient, which is coconut milk.) (see related question)
You have the medicine man mix a sleeping potion, using coconut milk, a creature bone, and a key ingredient. The bone and green ingredient are down in the underground ruins. Once you have it mixed, you fire it from the shark feeding Coconut Cannon at Booga bay. (see related questions)
Somewhere in the temple.... 0_o :P
You need the three ingredients : the coconut milk, the creature bone, and the key ingredient. He will mix them into a sleeping potion for the shark (wear a grass skirt for him). The bone and key ingredient are underground in the ruins. (see related question)
The key ingredient is a green substance hidden in the underground ruins. It is used in making a sleeping potion, which you will feed to the giant shark. --- The other two ingredients are Coconut milk and a Creature Bone. You get free carbonated coconut milk from the stand when you arrive on Shark Tooth Island. The creature bone is in the same underground passages as the Key Ingredient. You will need to decipher the ancient writing to open the door under the ruins. Once you have the ingredients, the medicine man will mix them for you.