What type of fish make sea shells?

Answer 1

Short Answer:

Fish do not make sea shells.

Long Answer:

Sea Shell: the hard protective outer case of a mollusk or crustacean. That includes the calcium carbonate shells made by clams and snails and the chitin/calcium shell of crabs and lobsters and the like.

Fish: fish are a catch-all group that includes species with backbones, fins but no limbs, get oxygen through gills, and live in water. This includes hagfishes, sharks, bony fishes and more.

If you consider a sea shell to be anything hard you'd find washed up on the shore, perhaps you might consider fish bones to be a sea shell, but this would be wrong, because a shell is usually on the outside of an organism. Many animals are called fish which aren't fish, like starfish and jellyfish, but they are not true fish.

In the Devonian era, around 400 million years ago, fish with bony armored plates called placoderms swam the sea. This is probably the closest to sea shells you can get from a fish, since it's outside the body and hard, but they aren't alive today.

Therefore, since fish are vertebrates, and sea shells come from invertebrates, fish do not make sea shells.