The lancelet Branchiostoma lanceolatum is considered an invertebrate although the species bears quite some resemblance with ‘primitive fish’. It is possible to distinguish a head with a mouth surrounded by fine tentacles (used to gather food), a ‘body and a ‘tail’. The animal is covered with fins and manages to cover small distances by swimming; however, the lancelet is buried in coarse sediment most of the time.
Degraer, S.; Wittoeck, J.; Appeltans, W.; Cooreman, K.; Deprez, T.; Hillewaert, H.; Hostens, K.; Mees, J.; Vanden Berghe, E.; Vincx, M. (2006). The macrobenthos atlas of the Belgian part of the North Sea. <em>Belgian Science Policy. D/2005/1191/3. ISBN 90-810081-6-1.</em> 164 pp. (look up in IMIS)