Aspidosiphon (Aspidosiphon) elegans (Chamisso & Eysenhardt, 1821)  

This species is the most common and widespread Aspidosiphon in tropical regions, inhabiting coral rubble and soft rocks in shallow water. It is distinguished from it congeners by the presence of dark conical hooks on the posterior portion of the introvert. Asexual reproduction, rare among sipunculans, occurs by transverse fission into two unequal parts. A posterior constriction is commonly observed in specimens collected from the natural habitat.