Ancient stone tool?

The other day i was talking with a guest about the book, "Eriska- the story of an Island" and explaining how my father had researched the details in great detail and whilst I may have mocked him at the time I really appreciated all the work he put into it and indeed he had uncovered facts that I don't think even he knew and certainly I would never have learnt without his perseverance. Whilst the latter historyis part of stories passed from person to person the earliest chapters about the creation of the island and the early settlements involved much reading and research and uncovered many new details.

The guest had mentioned how accurate the book was and from his background in education and the knowledge he showed it was clear he knew what he was talking about and even clearer that I was out of my depth! in the discussion but having read and studied the book , I did manage to bluff my way through the conversation and soak up as much free information as possible for reuse in the future- (just trying to keep up with  my father!) 

Anyway the next day  the guest returned from a walk with a few items in a cloth bag and a bit like antiques roadshow he started to empty te bag and show me the items. Some were simple shells others distinctive stones but he did leave in his opinion the best till last in the shape of a smooth stone he found near the Crannog. At first glance it looked like  a simple piece of shist simply washed up on the beach but he explained that it may have been a tool for scraping hide many years ago ind indeed when he placed it bin his hand and offered a demonstration- who was I to argue! Anyway it now resides on my office table and makes a good story none the mess!