I follow a few steps to clean and preserve horseshoe crab molts.

1. First I thoroughly wash the shell inside and out, sometimes you have to let it soak for a bit to get things to loosen up a bit.

2. I then soak the shell in a solution of bleach and water. Approximately 1/2 cup to about 3 gallons of water.  I let it soak for about 20-30 minutes. This sterilizes the shell and removes any residual odor.

3. I then rinse the shell again to remove any bleach and dirt that may still be left on the shell.