isidium
noun
isid·i·um
īˈsidēəm
plural isidia
-ēə
: an outgrowth from the surface of the thallus in certain lichens that resembles a soredium
Word History
Etymology
New Latin, from Isidium, supposed genus of lichens, irregular from Isis genus of gorgonians + Greek eidos form; from the resemblance of lichens that have isidia to gorgonians