What is this?

[AndStand]

Does anyone have any idea what this is?
It's in a friend's garden and was pushing her slabs up. They removed a bit of the slabs and there's a basket ball sized "thing" under there. It's woody and there's something trying to sprout out of it.
I've looked at images of root burls? It might be?
There's a conifer about 12 feet away but that's it in the way of trees nearby.

Photo is loading!

Can you take a pic specifically of those beige 'sticks' please? Might help!

Edited: well actually more like bones?

Unfortunately not. I only took a couple of photos, and apparently the other photo is too large for MN. It's not as close up as this one anyway.

Fossilised dinosaur turd

😆

Yikes! The hills are that way >>>>>>>>>>>>>>

Possibly a tree stump?

Dare I say J....... k...w...? How long has that slab been down? Do any of the neighbours have rather overgrown gardens with very tall plants?

The photo is a bit blurry so any close up (macro) photos will help, especially as that sprout unfurls.

The slabs have been down for over 20 years. No other plants are nearby apart from a ceanothus, which doesn't look very old.
There's no Japanese Knotweed within the vicinity that we can see.