Body laterally flattened, oval in profile, varying in color from yellowish brown to tan and gray; becoming darker with age. Head profile of nape and snout straight. A yellow-gold crescent above the eyes. Base of pectoral fin with a black spot and a black saddle on the upper base of the tail.
Juveniles yellow, with a black saddle on the upper base of the tail and a larger second dot on the back and dorsal fin, which is lost with maturity (S. planifrons-juvenile).
Size up to 13 cm.
Inhabits inshore and offshore reefs, down to 30 m. Found within caves at night. Feeds mainly on algae, but also on harpacticoid copepods, small gastropods, eggs of mollusks, sponges, polychaetes and hydroids. Juveniles feed on external parasites of other fish. Pugnaciously guards large territories, will chase and nip intruders of all sizes.
Common South Florida and Bahamas, abundant to common Caribbean.