They probably crawled up the bowl into the water inlet holes around the rim. Put one of those toilet cleaning tablets in the tank and give it a few flushes.
My favorite thread thus far! I syphon into the toilet and bathtub whilst filling a watering pot for my house plants. This hasn't happened to me...yet! Maybe they will get rid of that ring around the bowl (lol)? Thanks for the laugh!!!
I checked the last 2 nights and couldn't find any MTS so maybe it was just a pair of stragglers from the last water change. I'll be sure to take a picture if I ever see them again.