These earrings are based on the auger snail that lives in an auger seashell (Terebridae). I imagine this creature lives up the entire length of the shell getting smaller and smaller at its tail end, although most likely it just grows bigger eating and lives in the open end.
Note ear hooks are not supplied. These are readily available from jewelry craft stores. The mouth is open so a colour stone can be glued there if wished (although I have not done this as I don't think it is needed).
The photo is of one printed in (plain) silver, which is nice. Although tests in alumide and plastic are good too.