Hello, I was using a chisel on rocks, and this immediately caught my attention, hair/root like strands trapped in this rock, they are definitely look not fossilized, as they bend freely, they are about 4cm long. Theres also this much bigger circular-like thing.found in Northamptonshire, UK which is mostly Jurassic in age, thanks. I don't think it's modern, as it was completely surrounded/trapped in rock, and the rock was very hard.
The camera was really not good at catching these fibres in a picture, sorry. Also, sorry if I do not reply quickly, the internet is having a few issues.