Found this on Monmouth beach at Lyme Regis... caught my eye because of the parallel tracks that trace the circumference of the flared end... but is it a fossil bone or just a rock??
It looks like (modern) bone to me.
But we need to know if it is bone or stone - how heavy does it feel?
If unsure, determine its density by weighing it and measuring its volume (by water displacement).
Then it is stone not modern bone.
Some more photos would be useful.
I suggest you get the folks at the Lyme Regis Museum to comment