WHY?!?

       What is the story with these Space-faring Snails?  I saw one today up in a higher one of Annabelle's dying flower clumps.
       I had need to move this upright slightly to try a different Blip.  It didn't happen - BUT - I heard a TAP sound at about ground level; deduction?  A third Snail had been dislodged and hit a lower bit of wood