A black splotchy lichen, possibly introduced from the U. K.

It’s found on barnacles in the mid intertidal but also on other calcareous substrata in moist situations, on wet sand, or on calcareous to acid rocks in freshwater or marine habitats.

Uses the suns energy.

Most lichens are a symbiotic relationship between a fungus and an algae.

Photo Credit: Rod Morris. Photos available from www.rodmorris.co.nz