Of course, you can also find shells of bivalves such as oysters on the beaches in the ABC-islands. And one of the families you can encounter is the genus of the Spiny Oysters.
Marine snails which are part of the Nerite family often have small teethlike protrusions which can often be found on the mouth plate (columella fold), the calcerous part at the opening at the bottom of the shell where the slug’s body moves to the outside.
This snail and shell species has quite a name in English: the Bleeding Tooth Nerite. It is kind of logical though if you take a good look at the shell this snail species builds for itself.