Amygdalaria

Amygdalaria is a genus of lichen-forming fungi in the family Lecideaceae. These lichens are typically found growing as crusts on siliceous rocks in arctic and alpine environments. Members of this genus form crustose thalli and are distinguished by their unusually large, smooth ascospores enclosed in gelatinous sheaths. The lichens have cephalodia containing Stigonema, a blue-green alga that enables nitrogen fixation....read more on Wikipedia.