...Almost certainaly not.
It is a piece of nodular flint. These arise in all sorts of shapes, some of which can look superficailly like something particular.
Have a look at this thread
and especially this blog page by Luanne
West Runton, Norfolk is a good locality for fossils. Look out for sea urchins, fossil wood and small mammals. You may like to take a sieve for the smaller material.
I expect you know about the West Runton 'Mammoth' - you can learn more about this at:
Thank you Mike for your useful comments regarding the flint and chert.