This rock was found in Lake/Lac Clair near Sturgeon Falls Ontario Canada in about 2 feet of water next to the edge of the lake. It can easily fit in my hand. You can see a size comparison in the first picture with the rock next to a Canadian quarter.
There is a fair amount of metallic sparkle when you hold the rock in the light. The bumps on the rock shine a little brighter than the rest of the surface. The rock is not very heavy and actually feels a little lighter than expected. The surface flakes a little but it doesn't leave residue on your hands.
I assume the slight brown colouration on one side is film from the lake floor but it doesn't rub off. The colour in the photograph is pretty accurate.
Thank you in advance for any information that helps identify this rock.