RollyGhost

I think you may be right. I found an old post from someone who found some off Lake Michigan a few years ago and someone had mentioned scoria to them. 

I suppose porous like lava rock would actually be a better description. 

Does anyone know what this could be? I've searched everywhere and haven't seen anything like it. I found it on a beach off Lake Michigan. It's very porous like charcoal, but also metallic. It barely scuffs glass, but also starts to crumble under the pressure of a scratch test. It leaves no color on paper. It's roughly .45 x .6 x .8 inches and weighs 2.0 grams. 

Is it just charcoal from a grill that underwent some process to make it shiny? Something else?