Need some help identifying snail slug thing

[LucasJ]

Dose anyone happen to know what this guy is and if it’s good or bad for my tank I have no clue how they got in my tank but they only come out at night and they breed in my sup like crazy

 

[C. Eymann]

stomatella, good guy

 

[eschaton]

Yeah, a fantastic algae eater - basically a freebie part of your "clean up crew."