This is weird, my favourite tank inhabitant, the strawberry conch completely disappeared a month or so back.
After a while I assumed he was dead and last week run my hands all through the sand and couldn't find any sign of him. I had taken him out a while back to clear some bubble algae off his shell, I kind of thought I'd accidentally put him in the bin with the newspaper i'd used to cover the floor... 🙈
Anyway out of nowhere he just popped up tonight right at the front of the tank and hopped along like nothing happened. F knows where he's been 

They do that....I had just supposed it was how they behaved in the wild ,scoff,sleep....