Yes they are eggs. If after a few hours you start noticing a cotton wool type fungus growing on the eggs, there is a very good chance that all, or some of the eggs are infertile. Unfortunately, the fungus may start attacking good eggs as well. There's not a lot you can do about this. This is one of the reasons why methylene blue is used, it can help to prevent and treat fungus on eggs. A word of warning! Adding methylene blue to your main tank could destroy your biological filter. In other words, you will lose all your beneficial bacteria.