Fat Homer
periwinkles are a freshwater snail.
Here in the NC mountains they are plentiful in cold fast flowing streams and rivers. They are usually found grazing on the alga that forms on the smooth stones and rocks.
This is a interesting question. I’ve wondered myself if they could be any harmful things past to aquariums.
I have collected them, as well as the crayfish that can be found in the same streams for feeding fish before. I haven’t ever had any problems.
But, that’s not to say I didn’t put my fish at risk by doing it.