Help ID -- Amphibolips confluenta, spongy oak apple gall

I found this in the yard, not anything I can ID, or even guess what it might be. Definitely not anything I have seen forming on a plant. Might have been left from last fall, that area hadn't been cleaned since last summer.



Super lightweight and fragile, the damage on it lets you peek inside, there's some kind of fluffy seed stuff inside.

Zone 6a/b Southwest Missouri.  

What can this be? I'm pretty puzzled.

more likely a gall than seed-related. kind of like a tumor that a plant grows in reaction to some bacteria, fungi, or insect.

this kind can definitely have some weird fluffy interior textures.

Looks like Amphibolips confluenta: Spongy Oak Apple Gall.

Thank you Greg and Joseph!
That would be off the neighbor's oak tree then. This explains why I didn't recognize it as a seed pod off any of my plants.
Thank you!!

:D

Looks like Greg and Joseph are right:

source

backyardnature wrote:Normally in such galls, in the center an egg hatches into a wormlike larva, the larva feeds on the gall tissue around it and grows, metamorphoses into a quiescent pupa, and eventually from the pupa an adult wasp emerges.

From the same site: making oak apple ink

Yup - we have them all over the place.