(photo of Adam Petrusek, Czech Republic: specimens from Red Sea)
(photo of Bernard DUPONT: specimens from Malaysia)
Calliactis polypus is easily recognizable anemone symbiotic with hermit crabs. It is widely distributed in tropical areas and specimens from different regions look very similar, compare the photos published here - one is from Red Sea, another from Pacific, and the specimens are identical. Other species which live in symbiosis with hermit crabs are Adamsia and Verrillactis.
Update from 03 November 2019:
Gusmao, Rodriguez and Daly (2019) synonymized genus Calliactis with Adamsia. In accordance with International Code of Zoological Nomenclature the older name (Adamsia) must be used for all former Calliactis species. Above named authors are of another opinion, and a corresponding request has been sent by them to International Commission on Zoological Nomenclature. For details see Adamsia palliata
Taxonomy:
Phylum Cnidaria
Class Anthozoa
Order Actiniaria
