Microscopic view of the coral polyps of Paracalyptrophora sp. and Acanthogorgia sp. showing the differences in polyp morphology between species. Polyps of Paracalyptrophora are downward, and arranged in whorls whereas Acanthogorgia has non-contractile polyps projecting outward from the axis. Also, Paracalyptrophora has larger, flat sclerites whereas the sclerites of Acanthogorgia are thin, and spine-like.