All Princess's eggs have been fertile but my other female Yoshi had a few infertile eggs. In fact we only had 2 hatchlings from her but they're both beautiful just like Yoshi. She might lay them in the moss - I haven't had any moss in with mine for ages. Mine don't seem to like it for some reason. If you want to get some vermiculite you can usually find it at pet shops, garden centres or online. I wish I had some more eggs to look forward to but the only eggs in my incubator are Bearded Dragon eggs that I'm incubating for a friend.