Gyalectidium areolatum

Gyalectidium areolatum is a species of lichen-forming fungus in the family Gomphillaceae. It is a leaf-dwelling lichen found in the Neotropics, particularly common in northern Argentina and Paraguay, with records also from Mexico and Brazil. The species is distinguished by its strongly segmented thallus that breaks into discrete, whitish polygonal patches separated by thin greenish zones, with well-developed scale-like reproductive structures developing at the margins of these segments....read more on Wikipedia.