Mysterious pulsating sand

[lastlight]

Have a wrasse that disappears in the evening?

Mine both like to 'explore' underneath the sand even when they're not going to bed. Just today my leopard dove under and it looked like the movie tremors as he literally moved through the sand (a good 6 inches). He popped halfway out of the sand and paused like that... just his head showing. The sort of thing you'd kill to snag a photo of but never going to happen).

[argan]

I don't have any wrasse, so it can't be them. Wanted to look with a red flashlight but can't find mine right now.

[reefwars]

i would think its def your pistol shrimp thats what they do is dig and plow sand, mine has tunnells through out all my tank.