, also known as cuttlefish bone
, is a hard, brittle internal structure found in all members of the family Sepiidae
, commonly known as cuttlefish
. Cuttlebone is composed primarily of calcium carbonate
. It is a chambered, gas-filled shell used for buoyancy
control. The microscopic structure of cuttlebone consists of narrow layers connected by numerous upright pillars. Depending on the species, cuttlebones implode
at a depth of between 200 and 600 m. As such, most species of cuttlefish live on the seafloor in shallow water, usually on the continental shelf
In the past, cuttlebones were used in making polishing powder. The powder was added to toothpaste and used as an antacid or as an absorbent. Today, cuttlebones are commonly used as calcium-rich dietary supplements for caged birds, hermit crabs, and turtles.
Because the cuttlebone is able to withstand high temperatures and also be easily carved it makes for an ideal mold making material for small metal casting. Jewelry and small sculptural objects can be produced quickly and economically. Jewelers prepare the cuttlebone for use as a mold by cutting it in half and rubbing the two sides together until they fit flush against one another. Then the casting can be done by carving a design into the cuttlebone, adding the necessary sprue
, melting the metal in a separate pouring crucible, and pouring the molten metal into the mold through the sprue. Finally, the sprue is sawed off and the finished piece is polished.