What is this rock?

I found this rock last year in an area of Wyoming known for its petrified wood. This, however, is not normal wood, but I believe is it petrified “something”. I just don’t know what. Any suggestions are welcome.

It defiantly appears to be organic in origin. The dimples are arranged in a somewhat geometric pattern around the surface, and there is a small straight crack connecting each dimple.

The coloring on this rock is unlike anything I’ve seen. White, purple, blue, green, and yellow. The greens look like moss, but I have scrubbed it clean, and the surface at least really is that color.

Now for the really fun part.

The inside of it is weird! And cool! This is where my understanding really starts to break down. It looks like a bunch of seeds inside it. But if the round things inside are seeds, what is the whole thing? A seed pod? An egg?

Here’s a better view of the inside. The shell appears to be agate, definatly silica based, though. If needed I can take better pics of any specific part to help identify it. If anyone can tell me, or even guess, what this is, that would be great.

Until then, I’m gonna keep calling it a Dragon’s Egg.