I've never done it with chameleon eggs...don't know why I haven't...but I have done it with turtles, coneheads, various geckos, water dragons, etc. Its neat to see! With ones like the coneheads and water dragons you can see the arms and legs and tails thrashing around inside. I don't do it much though....I'm not sure if the light startles them or not once the eyes have developed far enough.