Planted Tank Guru
Join Date: Feb 2010
Location: Newbury Park, CA
Those look like snail eggs to me and will just scrape off the leaf without damaging it at all if you don't want snails in your tank.
Most small snails eat algae, biofilm and dead plant material and don't harm plants. They can build into a real plague if plants are producing a lot of dead material or the tank is overfed. I figure if there are are too many snails it isn't their fault, I need to do something to reduce the opportunity for so many snails to survive. Have found that the numbers will drop once there isn't so much food for them because the plants are doing better.