snail death

So, a snail in my dad's tank died. It's been there for at least a year, I don't remember. However exact age is unknown since it was a river snail. I think that most likely one of the other fish ate it, but he insists it was old age. I highly doubt that because that's his go to whenever...

My tank has a serious algae problem. The only place to put my betta tank was by a window, and now there is a constant film of algae covering everything. Now, I wanted to add a nerite snail to the tank to help eat some of the algae, but, after moving around for a day, he stopped moving and died...

I've had a nerite for three or four months now, and a few days ago I found it upside down on the bottom of the tank. I gave it a sniff, it was alive. Anyways, I placed it on top of a decoration a few days ago, and it hasn't moved since then. I pulled it out of the tank today. It smells more...

Hi, I keep 2 Mystery snails in my tank.  This morning when I went to go feed the fish, I found a snail up at the top of the heater.  I'm not sure if it was floating or had latched on, but there seems to be a large fleshy part torn from the snail and protruding in front of it.  The shell is...