Haave to disagree with this.Neritina is solely an algae eater, no food leftovers, no plant matter. They also prefer only some type of algae, never the wafers.
That is the reason why they sometimes die in the tanks, nothing they like to eat. They are a bit fussy. Had mine for four years but I take care to not wash at least one fishtank glass so they have stuff to eat for sure.
In established tank they should be ok as others said.
My Nerites love blanched cucumber, broccoli stalk or courgette.
I cut a bit about a 1/4 inch thick, blanch it and when it'c cooled put it in the tank (often it floats, but sinks eventually. Nerites enjoy it and so do Amano shrimp). I discovered this when I put a lump in to catch a snail invasion which came in on a new plant. The Nerites are actually comical to watch, hugging the veg - I swear you can hear them going "Nomnomnomnomnom".