Crazy, I did check but found nothing. Someone on another forum suggested it was a pinched mantle and the only thing to prevent it was a 30 min. FW dip.
Does this make sense to you?
You should check for fireworms on the bottom of the clam. Once it happened to me that a fireworm crawled up the foot and ate it from he inside out. Fireworms tend to do that, luckily I got mine out before it did any more damage. Good luck to you.
No pics to post. Unfortunately it's gone. No signs of worms or snails.
Most likely a protazoan infection, or so it has been suggested.
Thanks everyone the help and suggestions. Within an hour of posting I had a dozen responses and suggestions. Try getting that level of support on RC! I'm glad to be a part of this community. Only wish I had found you guys years ago.