Hutchinsoniellidae

The Cephalocarida (from Ancient Greek κεφαλή (kephalḗ), meaning "head", and καρίς (karís), meaning "shrimp") are a class in the subphylum Crustacea comprising only 12 species. Both the nauplii and the adults are benthic. They were discovered in 1955 by Howard L. Sanders, and are commonly referred to as horseshoe shrimp. They have been grouped together with the Remipedia in the Xenocarida. Although a second family, Lightiellidae, is sometimes used, all cephalocaridans are generally considered to belong in just one family: Hutchinsoniellidae. Fossil records of cephalocaridans have been found in the Ordovician Castle Bank site.