Bigfin reef Squid, Sepioteuthis lessoniana, commonly known as the glitter squid or oval squid, is a species of loliginid squid. It is one of the three currently recognized species belonging to the genus Sepioteuthis. Studies in 1993, however, have indicated that bigfin reef squids may comprise a cfyptic species complex. The species is likely to include several very similar and closely related species. Bigfin reef squids are characterised by a large oval fin that extends throughout the margins of its mantle, giving them a superficial similarity to cuttlefish. They are small to medium-sized squids, averaging 3.8 to 33 centimetres in length.