pearly-shelled mussel

NOUN
21 LETTERS · STARTS WITH P

pearly-shelled mussel is a valid 21-letter word worth 30 points in Scrabble and 35 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
P3E1A1R1L1Y4-0S1H4E1L1L1E1D2M3U1S1S1E1L1
3 + 1 + 1 + 1 + 1 + 4 + 0 + 1 + 4 + 1 + 1 + 1 + 1 + 2 + 0 + 3 + 1 + 1 + 1 + 1 + 1 =30 PTS
DOUBLE WORD → 60TRIPLE WORD → 90
MEANING

What does pearly-shelled mussel mean?

NOUN · 1 SENSE
1

The pearly lining of the dark shells is a source of mother-of-pearl.