Areolate

Areolate lichens are crustose lichens (that is, lichens that grow like a crust of paint) that appear to be broken up into somewhat polygonal pieces like old cracked paint. The pieces are called aereolas (areaeolae).[1] The appearance is similar to the island-like pieces of dried-cracked mud in a dry lakebed. The areaolae "islands" are connected by an underlying prothallus to make a single lichen organism. The prothallus is often dark and not noticeable, whereby the different aereolae appear to be disconnected. Sometimes the aereolae curl up at the edges and continue growing at the edges so that they overlap, which is called being squamulose.

Colony of Caloplaca sp. on rock.