Mystery snail eggs can take anywhere from 10 days to 4 weeks to hatch. How long they take to hatch depends on different factors including temperature, humidity and even size of the clutch (larger clutches take longer to break down causing it to take longer for the snails to be able to escape the eggs into the water.
My egg clutches are kept in a warm room so they typically hatch in 14 days. The eggs of two clutches were photographed each day until hatching so that you can see how they change over time. The most common question I hear is are my eggs fertile and do they look like they will hatch.