they look like pond snails to me,i could be wrong. i got about 1.5 million of them between all my tanks some people consider them a nuisance i like them the keep my tanks clean and don't eat my plants. you can keep the population down by reducing feeding and getting there eggs out before they hatch the eggs look like white dots in clear jello good luck
if you want to make some yoyo loaches happy add a few to your tank, they are a lot of fun to watch. The down side is they do route around int he substrate. And don't freak when you see them sleeping on their side. They are not dead just sleeping...
I like pond snails because they crush easily and fish love eating their guts. :icon_mrgr
Known as the "fruit fly of malacology", because they breed so easily in a huge variety of conditions, and have been studied so deeply. They procreate sexually but can store allosperm for later use and self-fertilize if needed. I have never seen controlled feeding effect their population, have even had them survive and continue to colonize in forgotten buckets of water and plant clippings, no food or anything added for a year except for top-offs. Still, pond snails out the yin yang.
These can be a real nuisance. Once I had them, I decided to add Malaysian Trumpet Snails to compete with them--it works, too. Then, I had green algae I wanted controlled and otos would not live in that tank, so I got red ramshorns. They were VERY effective. Now this 10 gallon tank has lots of ramshorns and MTS with only a few pond snails. MTS and Ramshorns are a lot more attractive and beneficial.