Night anemone

Scientific name : Phyllodiscus semoni

Strange anemone, during the day it appears like a spongiform body, actually at a closer sight is an intricate mass of branching vesicles, of variable colour (green, yellow, orange, brown, grey). At night, at the center of this mass, a white translucent column appears, with long, slender tentacles. 30 cm of basal diameter.
It can not be confused with anything. At a first glance it could resemble a sponge.

Associated organisms
With microscopic Algae, giving the typical colours. Often hosts commensal shrimps, typically Periclimenes venustus.