Abstract
An unusual colonial ascidian with 1-2m in length, belonging to the genus Aplidium (Ascidiacea: Polyclinidae), has been sampled from the Strait of Gibraltar (Ras Leona, Morocco). The characteristics of the colony, zooids and larvae point us to A. proliferum. The species seems common in the NE Atlantic from the Shetland Islands to Mediterranean Sea, but it never has observed the size of colonies as found in this area, the Strait is the largest so far reported, which it is probably represents one of the longest ascidian worldwide.