I have a zebra nerite and one of those called red onion or racing track nerites. I bought them both in July 2011. I find it incredible that snails can live this long. Their shells are very much showing their age but they are still alive and munching algae. I also have a yellow and black striped nerite bought in December 2013, and a grey one with white speckles bought in December 2014. The last one is in my betta's tank and has tufts of algae growing on its shell.
But I have also had snails die for no apparent reason much younger than these.
Word of warning - they can and do lay sesame seed-like eggs which never hatch. They can be scraped off hard things like the tank walls and rocks but they are virtually impossible to remove from wood. I used to have three of the grey ones, and one would lay eggs like there was no tomorrow. I had to separate it from the other two in the end, that stopped it laying eggs.
But I have also had snails die for no apparent reason much younger than these.
Word of warning - they can and do lay sesame seed-like eggs which never hatch. They can be scraped off hard things like the tank walls and rocks but they are virtually impossible to remove from wood. I used to have three of the grey ones, and one would lay eggs like there was no tomorrow. I had to separate it from the other two in the end, that stopped it laying eggs.