When I was at the Tucson fossil show I picked up several slabs of unprepared Green River fish from the 18-inch layer.  I've been working on this Knightia and have a few questions.  I only have hand tools so I have been carefully removing matrix using some pin vises with various needle tools I picked up from PaleoTools.  Here's how it looks so far:   First question:  If you look in the areas of the anal fin and the dorsal fin, there appear to be random swatches of organic material