Marine isopod (likely cirolanid isopod)

Marine or brackish coastal waters, especially beneath rocks, seaweed, driftwood, and debris. Some species inhabit beaches, estuaries, or submerged caves.

Many are scavengers and omnivores, consuming carrion, algae, detritus, and small animals. Some cirolanids actively prey on or feed from fish and other marine organisms.

Flattened, armored bodies and numerous walking legs suit crawling through sediment and crevices; they swim when disturbed. Females brood young in a ventral marsupium, producing miniature juveniles.

Generally harmless to people and beneficial as scavengers that recycle organic matter. Certain marine isopods can damage or parasitize fish, but this specimen is not identifiable to species from the photograph.