The Callistoplax retusa chiton is a small to medium-sized marine mollusk in the class Polyplacophora, found along rocky shores of the eastern Pacific. Like other chitons, it has a low, oval body covered by eight overlapping shell plates surrounded by a broad, leathery girdle. In C. retusa, the plates are typically dull gray to brown and finely sculptured, while the girdle may be textured with small scales or bristles, helping it blend into rock surfaces. This chiton clings tightly to rocks in the intertidal zone, where it grazes on algae and microscopic organisms using its rasping radula. Well adapted to wave-swept habitats, Callistoplax retusa is most active at night or during high tide and plays an important role in controlling algal growth on rocky reefs.