The mystery slug

It's been raining a lot in Loja recently, and I've come home a couple times to find slugs hanging out on my bathroom floor. This is in part my fault because I like to always leave the window open; it gets really hot and humid in my room if I don't. Anyway, I think there's an undiscovered slug that does laps around my room when I'm not there. I keep finding these mystery slug trails and no slug. I found one on the hood of a sweatshirt that I had carelessly left on the floor of my room one day. And 3 days later, I found a trail snaking all over one flip flop, but not the one next to it. And this keeps happening randomly. I have taken to looking at my floor very carefully before I walk anywhere barefoot, but this is a very crafty slug. I don't know what to do about it.