My mum bought this from a charity shop thinking it was a fishing weight, maybe it is, but it's a funny shaped one. It measures five and a half cm diameter. It kind of looks like it's been buried somewhere or maybe it's just old, not sure. There's a dent in it, like someone hit it with sharp object and recently. I tried cleaning it but the muck doesn't wipe off. Anyway, there seems to be a boat on it, and some zigzag lines under that. I've been searching through everything, medals, weights, medallions, pendants, seals, discs, etc. Found nothing, it's probably nothing i guess. She only paid 50p for it, and ideas?