What are these?

Saw these wooden things at Hare Park,Chippenham near Cambridge. They are wooden and look as if they are tree roots of some form, but they look odd. They are about 3m from the tree.

[Dione Giorgio]

My impression was that these are rocks very interesting shapes and tones.

[xbm]

@sangwann - these were wooden, not rocks.

[Tony R]

It would be interesting to see if they grow more shoots