I agree with Aydin.  If the specimen is for display purposes and you want to
clean it up, leave it in the alcohol for a few days, then take the specimen
out and wash it in water with a little detergent, to remove the slime and
coagulated fat deposits.  You can use a soft brush to get into crevices.
Rinse well under running water, and return to fresh alcohol.  Even if the
original alcohol looks clear, replace it, as it has been somewhat diluted by
water from the snail tissues, and probably contains other dissolved
substances as well.

Paul M.