Petrified knife hones from Lough Neagh

 Lough neagh is the biggest freshwater lough in the British Isles and in years gone by there were pieces of petrified wood taken from the lough and fashioned into whetstones to be sold in the cities for sharpening knives, you can occasionally still find pieces of petrified wood along the shore line if you look carefully.. 

It looks just like a piece of drift wood

But when you pick it up you can feel from the weight that its not wood.

And when you tap it against another stone the clink sound is unmistakable, it'll take a bit of work to make it into a whetstone but I think I'll keep it just as it is, after all its supposedly 60 million years old !