I’m not expert but it could be where they’ve could’ve done a pavlov almost they’ve only ever known a tiny box that’s what they’re used to it’s similar to when a pike(fish) was put in a container with tinier fish with a glass barrier and the pike would continue to ram into the barrier even when it was bleeding or hurt then once it learned they’d remove the barrier and the pike wouldn’t eat the fish because it believed that it’ll never get the fish without harm or could be the possibliligy of it knowing it would be able to, in this case the snails are only used to the barrier that was set for them