And we have a winner!! It is in fact a nassarius snail. No idea if it is a tonga nassarius snail but it is definitely a nassarius snail. He started climbing up the glass and his shell kinda started hanging off him. I moved him to the sand and then he went right back up the glass again, moved him again. The third time he went up the glass no one was home to move him and it fell off. So far, it's been about 2 1/2 days and he is still running around the tank naked! As far as I can tell he was very determined to run naked...