Finger Leather Coral (Lobophytum pauciflorum) イボウネタケ
I think that this is Finger Leather Coral which is a type of soft coral. Some have the polyps contracted and most have the polyps extended. Amami 2025
Looking closer at the Finger Leather Coral with the polyps extended. Amami 2025
Looking even closer at the Finger Leather Coral details of the polyps can be seen. The dark spots between the polyps are pores that take in water to expand the colony when feeding. They expel water to contract at rest. Amami 2026