they will probably survive. mine hatch and i get some little things crawling around on the glass for a day then a few weeks later at night i see little tiny snails. they look like cerith eggs to me (not sure if you have those)...thats what they are in my tank. I started with 5 cerith snails two years ago, haven't bought any more, and now have a total population of probably 15 or so...considering my crabs kill some and natural die off rates I don't think I am doing so bad