Hello there, I wasn't bothered by this at the beginning but their population seems to be growing, so I thought I should ask around and see if there's anything that I should do. The size of these things are very tiny, as tiny as half size a grain of sesame. They seem to have transparent skill shell and easy to crack when I pick it up with a twister. They only appear at night, and visible on the grass. They seem to crawl in extremely slow speed and if I scrap that off and the fish sees it, they will eat it. They also appear to be active at night as I never see them during the day but on the grass in the early morning. I believe that my filtration system and water quality is very good. Has anyone seen this? I wonder if they're baby snails.. Thank you.