Identification required! Misformed acorns?

[Ryan]

Can anybody educate me as to what these items growing on oak trees are. I have came across these many times in the last couple of visits to this job. They are approx 20-25mm in diameter.

 

 

[sloth]

It's a gall caused by a cynipid wasp...

[Ryan]

Thank you. Just googled it and found some good info. Quite fascinating really. Cheers.

[Jesse]

Its actually called Marble Gall, as its appearance suggests, and what Sloth said.

[Thewildwoodman]

Great ID, there are loads of these things on Oak from the spangle gauls on the leaves to the knopper gauls, marbleson the acorns. And the chunky Oak apples. It's amazing what a chemical reaction can produce in trees as a result of an egg being laid....

[Jesse]

Great ID, there are loads of these things on Oak from the spangle gauls on the leaves to the knopper gauls, marbleson the acorns. And the chunky Oak apples. It's amazing what a chemical reaction can produce in trees as a result of an egg being laid....

 

Yep I agree, it really is amazing whats up MN,s sleeve.

[peatff]

We always called them oak apples, if you look at them you can see where the wasp grub came out usually.