So I have this small block of Green River matrix that has fish material. When I got it, A part has been prepped, exposing most of it, but then I checked the corners, saw more covered material, and realized that it could be prepped even further. The problem is, I don't have any prepping tools because I've never prepped a fossil before But maybe is there any household tools that could efficiently prep Green River matrix? I just need to remove one tiny layer.