One additional note I meant to include the other day in my post on shell smell. (Sandro's question on uncurling chitons reminded me of it, even though my point has nothing to do with chitons). Sometimes when a mollusc is allowed to "biodegrade" instead of being promptly removed from the shell, the operculum absorbs some of the resulting foul-smelling fluid. Occasionally, with a larger operc, this can be so bad that even after the shell is thoroughly cleaned, you don't want to display it with the operc in place. I have had good luck eliminating this problem by soaking the operculum in a strong solution of liquid dish detergent (1 part detergent to 5 or 6 parts water) for a few days, then rinsing with water and drying. Once completely dried, the odor is gone. This technique is also useful for flattening opercula that have dried in a curled position. Have you ever tried to "unbend" an operc, only to have it snap in half? The detergent soaking makes them flexible enough that they can be flattened. Then, rinse them, place them between two layers of absorbent material (several thicknesses of paper towel works well), and put a brick or some other heavy, flat weight on top. Leave them for a few days or longer, until they are thoroughly dry, and they will remain flat. Paul M.