i have 2 strange snail stories to share, and i hope for answers to these questions, especially if any of you are snail specialists.
First, i had been having a serious algae problem in a 10-gal about a year ago, so i bought a snail (species unknown, but nothing fancy or special). he crawled around the tank happlily for the first couple of days, but when he stopped moving around and didn't eat any of the algae, i just supposed that he was tired from his excercise the last few days. but he sat there for a couple weeks, and the lfs said that's normal. i picked him up, and he had a lump of stuff in his shell. i swished him around in the tank, and the stuff was poop. then the snail crawled around the tank for a day or so, then quit moving again. later, i picked him up and swished him around again, this time, yielding so much poo (or it may have been decayed snail, it was a different color than the other poo) that it turned my tank a funny cloudy color. i put him in the tank, expecting him to perk up again, but he didn't, in fact, when i looked at him again, i saw that his body was completely gone from the shell! i then threw it out. can someone explain this?
wait, theres more
my uncle has about a 40 or 50 gallon goldfish tank. he got one of those wal-mart snail in a cup things, just for the heck of it, and it thrived for a few months. the thing grew and even started to lay huge (about 1 in. diameter) egg sacs. my uncle, not wanting a snail breakout, threw the eggs out, having to throw out a sac about every month. then, he found the snail one day had crawled up to the intake, trying to get up into it, but its shell was too big and its body just stretched up into the intake, about 3 inches. my uncle took him out and he was fine for a couple of days, but did the same thing a few days later and this time, did not live to tell the tale. my uncle thought that the apparent suicide was due to the continual disposal of the eggsacs, resulting in depression (okay, maybe not that deep). but we still wonder what happened with the snails.
i had to share these stories, if anyone has opinions on this or any advice, please post.

First, i had been having a serious algae problem in a 10-gal about a year ago, so i bought a snail (species unknown, but nothing fancy or special). he crawled around the tank happlily for the first couple of days, but when he stopped moving around and didn't eat any of the algae, i just supposed that he was tired from his excercise the last few days. but he sat there for a couple weeks, and the lfs said that's normal. i picked him up, and he had a lump of stuff in his shell. i swished him around in the tank, and the stuff was poop. then the snail crawled around the tank for a day or so, then quit moving again. later, i picked him up and swished him around again, this time, yielding so much poo (or it may have been decayed snail, it was a different color than the other poo) that it turned my tank a funny cloudy color. i put him in the tank, expecting him to perk up again, but he didn't, in fact, when i looked at him again, i saw that his body was completely gone from the shell! i then threw it out. can someone explain this?
wait, theres more
my uncle has about a 40 or 50 gallon goldfish tank. he got one of those wal-mart snail in a cup things, just for the heck of it, and it thrived for a few months. the thing grew and even started to lay huge (about 1 in. diameter) egg sacs. my uncle, not wanting a snail breakout, threw the eggs out, having to throw out a sac about every month. then, he found the snail one day had crawled up to the intake, trying to get up into it, but its shell was too big and its body just stretched up into the intake, about 3 inches. my uncle took him out and he was fine for a couple of days, but did the same thing a few days later and this time, did not live to tell the tale. my uncle thought that the apparent suicide was due to the continual disposal of the eggsacs, resulting in depression (okay, maybe not that deep). but we still wonder what happened with the snails.
i had to share these stories, if anyone has opinions on this or any advice, please post.