Oct 19, 2016 #1 Kaysneezye Community Member View Badges Joined Oct 7, 2015 Messages 61 Reaction score 51 Rating - 0% 0 0 0 I believe it's a clam of some sort it opens and closes if you touch it or a fish swims over it.
Oct 19, 2016 #2 Tahoe61 10K Club member View Badges Excellence Award Moderator Emeritus Joined Mar 2, 2012 Messages 13,239 Reaction score 15,708 Location AZ Rating - 0% 0 0 0 Yeah looks like a bi-valve, harmless, a filter feeder.
Oct 19, 2016 #3 mushroomrob Active Member View Badges Joined May 9, 2016 Messages 141 Reaction score 168 Location California, US Rating - 0% 0 0 0 Strange. Never seen that before.