The small sea animals in this group are related to snails and clams, but don’t resemble them. Instead of large shells, they have spines, tiny plates, or worm-like bodies for protection.

Aculifera live in the ocean, often on rocks or buried in sand. They feed on algae or tiny particles of food and play an important role in the ocean food chain.

There are about 1,000 species in this group, divided into two main families: Chitons, which have eight hard plates on their backs, and Aplacophorans, worm-like animals covered with tiny spines instead of shells.