New observations but no answers yet.
The tiny dots continue to show up but no new snails appear in that tank.
I set up another tank where there is no "seeable snail" with just rock, shrimps, green carpet and macro algae. These dots appears in that tank as well. The only newly live appears on its own in the tanks are tube worms and baby feather dusters. I will continue to watch this tank for couple months and if for couple month later, there are no seeable snails come up while the dots continue to appear, I think it's safe to rule out that they are any of my snails' eggs. I will set up two 10G, one with a rock that I can see the worms are on there and one that does not, to see what's going to show up this time. I will try to clean out all the dots on the rocks if they are there. I start to have a feeling that these dots could be somehow related to the tube worms or baby feather dusters because these two seeable animals are the only lives shows up by themselves along with the dots in the green carpert tank. I will also try to note if the copepod plays a role here this time.