littleneck clam

NOUN
15 LETTERS · STARTS WITH L

littleneck clam is a valid 15-letter word worth 24 points in Scrabble and 31 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
L1I1T1T1L1E1N1E1C3K5C3L1A1M3
1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 3 + 5 + 0 + 3 + 1 + 1 + 3 =24 PTS
DOUBLE WORD → 48TRIPLE WORD → 72
MEANING

What does littleneck clam mean?