Alwyn (and others interested in cowries), For a period in the late '80s and early '90s, I 'tagged' many cowries while trying to accumulate data on growth rates. My method was to file notches--in coded positions and sequences--into the marginal callusses, at locations which did not seem likely to comprimise the shells' integrity. Some of these shells helped me determine that some cowries achive a final state of callosity and continue living afterward without adding more callus. This was mentioned in an article in the March, 1991 Hawaiian Shell News. It is also available on-line at http://www.cowrys.org/archive/NSN375CY.HTM#A Obviously, the less callussed the cowries were, the more difficult it was to not harm the animal and its shell, plus further growth would obliterate the 'tags.' I have two well-matured Cypraea sulcidentata which almost completely covered the notches I had put in them months before. Later, I decided on a method of shallower grooves in the dorsum, where growth was minimal and any commercial value was greatly reduced; an important consideration for scientific work. I hope that helps... makuabob (bob dayle), webmaster http://www.cowrys.org _________________________________________________________________