In general, this species is very similar to several Phascolosoma in terms of ecology and morphological characters.However, the digitiform villi of the contractile vessel of Antillesoma distinguish this species from any Phascolosoma. A further distinction is the lack of hooks on the introvert. The introvert is of variable length, but often about equal to that of the trunk. Numerous digitiform tentacles (>30 in adults) are arranged around the nuchal organ. There are 4 retractor muscles, but each lateral pair may be considerably fused, appearing as one muscleon each side of the nerve cord, with a small bifurcation near the origin. The longitudinal muscle layer of the trunk is divided in anastomosing bundles, which are visible through the trunk wall in small specimens. The trunk and the introvert are covered by papillae that are concentrated on the extremities.