Dear Artemia, even the very first image that I've posted concerning these echinodermal shells was a direct scan...
From my experiences of directly scanning nearly every object that was in my reach and that was suitable to lay on a scanner, I knew that the scanner light provides such fine diffuse lighting, and the effect is even more dramatic when you make your scans against a dark background provided by turning off the lights of the room that you're making the scan...
Rest is ideas, careful placements, and post work (if necessary)...

Well, I hope I didn't disappoint you with the simplicity of the technique that lead to an image that you liked quite much... :-)