I see your having trouble with them still, arrow crabs eat them,lol but they look like spiders. There's a fish called a dolphin shark, I think that's what it's called. It's black and blue with a long skinny body. The only thing with them is they rearrange things trying to find the bristle worms. I had a dragon wrasse that would move rocks going after them it was crazy. My friend has a dolphin shark fish and it just digs and moves the sand around trying to uncover them.