Disk ascidian

Scientific name : Lissoclinum bistratum

Colonies in form of a small ball or disk, often many colonies close together. Brilliant green colour, small oral siphons around a common cloacal opening, larger.
Similar to other didemnids, like Atriolum robustum, but easy to distinguish due to the green colour. At a first glance it is possible to mix it up with a green algae, but the siphons are exclusive of ascidians.

Associated organisms
Green colour due to a symbiotic blue-green algae, Prochloron. Often epibiotic on branching corals.