Lancelet meaning

Any of various small chordate marine organisms of the subphylum Cephalochordata, having a long thin body with a notochord but no cranium or vertebrae, and usually found buried in sand.

Any of various small, transparent, fishlike marine organisms of the subphylum Cephalochordata that are related to vertebrates but have a notochord instead of a true backbone. Unlike other primitive chordates, lancelets have a body divided into serially repeated muscular segments.