Is it true that the lighter the shell color is, the more likely a mystery snail is female? I am trying to create a more balanced tank. I have only 1 female right now and multiple males, and I'd like her to have some female companions. However, typically you get the snails as juveniles and sex is difficult to tell at that point. Any advice about how to find females to add to the tank, and/or about shell coloring, would be great!