It is the cartilage which underlies and supports the radula, a ribbon of teeth.
[2] The feeding apparatus can be extended from the mouth of the animal, and the radular ribbon can slide over the odontophore.
By moving the radula and odontophore over a surface, the teeth cut and scoop up food particles and convey them into the mouth, whence they enter the oesophagus.
The diagrams here show the feeding apparatus of a generalized gastropod.
The details shown do not necessarily apply to predatory species such as the cone snails, which have a highly specialized feeding mechanism.