In immature specimens, the stipe has a complex structure of short branches but by the time the alga reaches maturity, only the scars of these remain.

[2] The green colour of the umbrella alga is caused by the presence within the cell of chlorophyll and the plant's energy needs are supplied by photosynthesis.

If the plant is broken in two pieces, each is able to survive and regenerate new parts, even the one that lacks a nucleus, although the anucleated fragment will die after a few weeks.

[2] The umbrella alga has the ability to remove mercury from sea water and concentrate the metal in its tissues in polypeptides.

This sinks to the bottom of the sea and begins to produce a new stipe which later develops several whorls of short hairs and eventually a new disc.