Can anyone help me identify this weird seed pod I found in the forest?

Question

I don't have a picture of this thing, but I've not been able to identify it for the life of me. While walking in the forest, I came across a bright, nearly neon-green ball with a stem. It fit in the palm of my hand, and was covered with small red dots. It had cracked open, and when I peered inside, there was a "fluff" (like the kind that comes out of milkweed in the fall) inside. Wherever a filament touched the inside, there was a red dot on the outside.

It and a few others like it were underneath some sugar maple and beech trees ...and I know that it didn't come from them.

My friends and I have settled on calling it an alien life form. Does anyone have a clue what it is??

Answer 1

Could be a cottonwood, or beach.

Answer 2

My guess is that it may not be a seed pod but an "oak apple" which is a gall on oak trees formed by a wasp.  The egg is laid on the leaf and the gall grows around the developing larvae.  This is what they look like:

http://www.flickr.com/photos/chickeninth...

cut open showing the wasp larvae:  http://www.flickr.com/photos/chickeninth...

They're starting to show up in the woods around me now too.

Some additional info:  

http://www.fs.fed.us/r8/foresthealth/pub...

http://www.jmu.edu/biology/k12/galls/oak...