My niece found this while wading in a lake in northern Ontario.
It seems to be polished stainless steel or chromed steel about 2 centimetres long and 1 thick. I know it’s steel as it sticks to a magnet. I have no idea what it is.
Update: Some of the comments indicate people think this is larger than it is. It’s like a bean. Maybe 1/2 inch by a 1/4..