I made an easel stand which consisted of 24" wood legs attached to the corners of 16'x20" empty picture frame that held a piece of clear glass of the same size. I placed a black piece of paper on the glass that had a hole cut out in the shape of the shell. I placed the shell over the hole so that only the black paper and shell showed.

I fired a small speed light placed below the glass which brought out the hidden colors of the clam shell. I used a small piece of diffusion material over the speed light to diffuse the light.