cup fungus

NOUN /kəp_'fəŋɡəs/
10 LETTERS · STARTS WITH C

cup fungus is a valid 10-letter word worth 17 points in Scrabble and 24 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
C3U1P3F4U1N1G2U1S1
3 + 1 + 3 + 0 + 4 + 1 + 1 + 2 + 1 + 1 =17 PTS
DOUBLE WORD → 34TRIPLE WORD → 51
MEANING

What does cup fungus mean?