These creatures all have skeletons made of hard plates or shells.

Some were covered with pink sugar, others with skeletons made of strands of dough.

Ray-finned fishes normally have skeletons made from true bone, though this is not true of sturgeons and paddlefishes.

Rugose corals have a skeleton made of calcite that is often fossilized.

Sharks are in a class of fish called Chondrichthyes, with skeletons made of cartilage instead of bone.

Because sharks have skeletons made of cartilage, they do not fossilize easily.

They use it to fashion the coccoliths shown here, their armoured skeletons made of chalk or calcium carbonate plates.

They have skeletons made of cartilage rather than bone.

Elasmobranchs, such as sharks and rays, are a very ancient group of fish that have a skeleton made of cartilage instead of bone.

Their long, narrow bodies have an external skeleton made of bony plates, and their mouths are very small and pipe-shaped.