Mystery snail eggs do not look like that, but their poo does. Sometimes you will see stringy clear thing hanging off of them, which is the poo. I have attached pics of my mysteries eggs.
I would recommend feeding your snails, which is going to be hard with the thieving goldie in there LOL. You might have to separate them when feeding. My one mystery (golf ball size) eats an entire algae wafer once a day.
When you touch the flesh of that snail, does it go back into it's shell? How long have you had the snails, two years? Have you taken it out of the tank and smelled it?
You can grind up cuttle bone and sprinkle it into the tank to help their shell grow.
I think the gold coloring on the body is just it's color.
I just picked up some peaches, oranges, apples and zuchinni today to feed my snail, on the advice of MGamer20o0.
you are so lucky!!! I want baby snails too!!! : )