Crappie from tidal water have those alot I've seen them in crappies from NC. VA. DE. and MD. We been just plucking em out since I was a kid and eat em and I'm 43 now . Knew a man that ate lots of em and he lived to 89. I was told that even if you miss one as long as its cooked good they won't hurt ya. You taught me something capt. mike I never knew they came from snails. Big black drum have worms too.