Cuttlefish are marine animals of the order Sepiida.
They belong to the class Cephalopoda, which also includes squid, octopodes, and nautiluses.
Cuttlefish have a unique internal shell, the cuttlebone.
Despite their name, cuttlefish are not fish but molluscs.
Cuttlebone, also known as cuttlefish bone, is a hard, brittle internal structure (an internal shell) found in all cuttlefish.
Cuttlebone is composed primarily of aragonite.
Described as a chambered, gas-filled shell used for buoyancy control; the siphuncle of the cuttlebone is highly modified and is on the ventral side of the shell.
The microscopic structure of cuttlebone consists of narrow layers connected by numerous upright pillars. (source)
So can hamsters eat cuttlefish or cuttlebone?
Yes they can have cuttlebone to chew on, so they can grind their teeth.
Cuttlebone isn’t bad for them and they will enjoy gnawing on it.
Many owners give cuttlebone to their hamsters to chew on and report that their hamsters have enjoyed them.