OK, so I got a fish tank last summer. It is a ten gallon tank and I had 1 blue gourami and 1 Dalmatian Molly. The Molly had a baby and died while I was away for vacation last august. I am away at school and having my family take care of the tank. They called me in September to tell me that there was a small orange shell with a snail-like creature inside that was walking around on the bottom. Every week when I talk to them they tell me there are more shells. I just got back for thanksgiving break and there are between 20-35 shells/snails, orange, about 1/8-1/4 in. in length. I am basically ready to clean this tank from top to bottom but I am so confused as to what is going on and where they're coming from. Help me Please!