Look up Japanese trapdoor snails, it looked pretty much like that to me, but like I said I haven't kept them. The more you feed the more most snails will reproduce. Not bladder, ramshorn or trumpet snails or mystery snails either, that pretty much sums up most of my snail experiences in 40+ years. Although recently I have very small, very flat rams horn spiral type snails I haven't had before, you never know what critters you may get. Maybe the shop you got it at would like some freebies? Not likely, but worth asking...You may have to sneak some out to the compost pile...& feed less!
Debris (food & poo) can go inside hollow decorations & stay in there rotting, molding & making a mess. The outside is likely only biofilm or algae, no big deal (snail & pleco food). Uneaten food & detritus can be snail food too, you may be very sorry...check soon!
BN plecos are pretty big for a 10g, even females, though smaller, get to 3 inches. Males can grow to 4+ inches. Let it grow for now if it's small. Awfully big for a 10g, males tend to hide, females are out & about more even when smaller IME.
Debris (food & poo) can go inside hollow decorations & stay in there rotting, molding & making a mess. The outside is likely only biofilm or algae, no big deal (snail & pleco food). Uneaten food & detritus can be snail food too, you may be very sorry...check soon!
BN plecos are pretty big for a 10g, even females, though smaller, get to 3 inches. Males can grow to 4+ inches. Let it grow for now if it's small. Awfully big for a 10g, males tend to hide, females are out & about more even when smaller IME.