Urochordata

Urochordata (Tunicate worms, "Sea Squirts") are saclike filter feeders with input and output siphons.

Some larval forms appear very much like primitive chordates or hemichordates with a notochord (primitive spinal cord). Some forms have a calcereous spicule that may be preserved as a fossil. Jurassic to Present with one proposed Neoproterozoic form - Yarnemia. Some workers class the Urochordates as a subphylum of the chordata.