We have one of cat trays located at bottom of stairs and I'm prob around same age as you Angie although bet my eyes are worse
We see slimy trails around said litter tray most mornings and have taken to calling the invisible intruder Bob the Slug. Anyway, I was coming downstairs not long back and saw this enormous, long, fat, browney, greyey, slimy poo in tray and thought "OMG not another vet visit" but on closer inspection realised it had little horns so obviously called up to OH to come and "say Hi to Bob the Slug"
Perhaps I shouldn't admit to this kinda thing in case you decide to come and rescue me babes from this mad house but of course it's Judith's fault for introducing us to Argo Baby Chick Crumbs coz obviously Bob loves em
We relocated him but he somehow keeps coming back from the signs of the slimy trail each morning
Oh and I had to hang up on me mom's pal on phone yesterday as a fist sized frog (toad?) was hopping past the french windows ............ inside the lounge......... relocated to pond 3 houses away........