HCA: Hermit Crab Association

Hi!
I just got a fun wall climber, but it reached the top. Now, one of my very energetic explorers is constantly crawling on the screen upside down. Is this risky or not a problem? I opened the lid while she was on it, unknowingly, and she fell Into the pool. She is back at it, bravely. I decided I can't open the lid unless everyone is off. What do you all think?

Yeah, they do like to climb! LOL!
No problem for them to climb, just be sure they can't escape!

Yeah I left it. It's just a new routine to check the lid now, before I open it. So far, no escapes. I've got plastic wrap, silicone mat, mini white board, and baby quilt on top. Pretty weighed down.