Andrew, yeah the crabs are pretty new age over there, I think it was the lid of an aerosol (so it gives you an idea of the size of the crab).
We are always hearing about the down side of all the plastic floating around the oceans, and whilst I dont condone it one bit, its great to see an upside now and then.
A couple of hours after I took that photo, this guy turned up on the door step too!
Andy, I'll shoot you a PM.