Hope this is real fossil, I would love to find one
Thank you all for help
It is a bit vague, but I think it is a fossil.
The golden bits are where minute cracks have had iron pyrites depsoited in them. That sometimes happens in association with fossils, but can occur indepently of them as well.
A similar pattern can occur due to the way fine-grained rock sometimes fractures ('conchoidal fracture'), but yours is different. The pattern is also a bit like that on a scallop shell, but again, I don't think that's the explanation here. Yours might be the crown of a crinoid (http://www.fossils-facts-and-finds.com/crinoid.html), but I really wouldn't put much confidence in that - the specimen is not clear enough.
If you know where it came from (and whether it was loose or in situ), that could help narrow down the possibilities. For instance, you could look-up the locality here - http://www.discoveringfossils.co.uk/
Ah - cross-posting...
I see where you're coming from Rhys, but I don't like the way the ribs look at the bottom-right - they seem to curve round a bit before joining what looks to me vaguely like the cup of a crinoid. ...And I can just about see plates in that potential cup....
Now I think I can see why the radial lines seemed to change direction near the central 'hub' - due to the 3D nature of that hub and the camera angle. I get the impression the hub rises up a little like a volcano - steepening gradually at first then much more further in. Is that true? If so, I have difficulty reconciling that with a bivalve. Bivalves can have a raised area (umbo) but in radial section it is usually/always curved the other way. That is, if you were to cut a section at 90degrees to the plane of the fossil and passing through the centre of the hub, a bivavle would be convex - whereas yours seems to be concave.
I'm not ruling bivalve out; I'm just having trouble 'seeing' it.
The age: we need to know where it came from and/or what the fossil is...
Without that, the best we can do is probably several hundred million years.