From my research there are 10,000 eggs per 6 inches. They incubate in 3-4 days.
They are most vunerable in their free float stage after hatching from shrimp and other carnivors and like to find a "dead spot" in the water colum to settle in, dig in the sand and grow their shells while eating microalgea and ditirius.
If you have a large number survive the free float stage and find a spot to hunker down keep an eye on your calcium levels as they could drop some from their shell growth.
They could also make it in to your overflow when in free float stage and wind up in your sump/refugium so keep an eye out there for them too.