Cowries are among the most cherished sea shells with collectors. The shells vary from less than 1 cm to over 10 cm, is very smooth and usually fairly thick. All shells are smooth on the inside, so the animal does not hurt itself, but cowries also extend and cover their shells, when they crawl around. The tissue of most gastropods only covers the inside of the shell and a narrow zone around the opening, but in cowries it also covers the outside, forming the brilliant gloss.

Young individuals have thin, elongate or globose shell with a large opening. The outer lip grows inward, covering most of the opening, in adults. Subsequently, teeth form on both sides of the opening, reducing it to a slit, and the shell thickens. All shells with a slit-like opening are adults, irrespective of size. Small and large cowries have the same shape, but young and old differ. As the animal grows older, the shell also gets thicker. There is a lot of individual variation, but heavy cowries of a given species are generally older than light ones of the same size.

The scientific Latin name is 'Cypraea', and common name 'cowry' is one of few Hindi words adopted in English. The Hindi term 'kauri' simply means 'shell', and has been adopted as common name in German and Scandinavian languages, but transformed into 'cowry' in English. The animals often live very long, small species to a couple of years, large species to over 10 years. Each species has a particular diet, but different species eat sponges, algae or even dead worms or fish.

Cowries have separate sexes, and the females lay 50-100 eggs in each capsule, that are joined to capsule clusters. Cowries evolved in the late Jurassic or early Cretaceous approximately 150 million years ago, but fossils are fairly scarce, and seemingly the extreme diversity is a very recent phenomenon.

An old friend, a passionate shell collector, told a relative going to the Pacific: 'if you see a smooth shell, the colour and size of a dark, reddish orange - buy it' That was when Europeans going to the Pacific were just slightly more frequent than snow in central Nevada, but I am still at a loss for a more intelligible description of the shell to the uninitiated. No other shell, probably no other organism, has this deep, reddish orange colour, covering the dorsum of the shell. It is not red, there is a distinct yellowish component, but virtually no blue or purple to make it brown, and the colour is very saturated. It is one of the few shells, you literally 'know from across the room'.

The name 'golden cowry' is a misnomer, as only old and dead collected specimens are yellow. Members of captain Cook's expedition were the first Europeans to see golden cowries as personal ornaments worn by chiefs in Fiji. The Polynesians held the shells in high regard, and only reluctantly parted with them. All of these antique specimens were yellow or yellowish, having faded over time or been collected on the beach, and had holes drilled in the side to hang from a string. Though imperfect, such verifiably antique, faded specimens with a hole are far more valuable than a live caught, perfect specimen. Faded and damaged shells are usually held in low esteem, but there is obviously first-class damage and then there is second-class damage

The habitat of Cypraea aurantium has been discovered in recent years, which is why it has also become available. It lives small caves and depressions in the ocean side walls of reefs, and is usually only active at night. The animal is dark and covers the shell completely - there is no 'glowing orange bulb' just waiting to be collected It is hard labour to collect a dark animal at night in 20-40 meter of water. The shells often have very strong growth lines or even repairs of the shell on the dorsum due to damages from the exposed environment.

I always wanted one of these Ever since laying my hand on my first shell book at the tender age of 9, I wanted a Cypraea guttata. Needless to say, it was a completely unrealistic wish, but the intricate, strong and yet graceful pattern had an unrivaled attraction.

Shells of Cypraea guttata are quite variable, depending on origin, and the connoisseur identifies distinct geographic morphotypes. This variation has led to the naming of several in part superfluous forms or 'subspecies'. Philippine specimens are usually more reddish than others, and have large, fuzzy snow-white spots. Japanese and Taiwanese specimens are often quite large with thin shells, brownish colour, poorly defined spots and ribs, but a very distinct dark blotch on the base. There are two types in the Andaman Sea. One superficially similar to Japanese specimens but with more distinct spots, and one that is comparatively small and broad with a heavy shell, strong ribs and small, sharply defined spots. This diversity makes it perfectly acceptable to build a collection of Cypraea guttata only There is an incredible range of colours, patterns, and sizes.

The first specimens were found in the stomachs of mollusk eating fish. Currently, most specimens are collected by means of 'tangle nets' in the Philippines, but occasional specimens show up from the Andaman Sea, caught by deep sea (100 meter) dredging.

The shells of cones are more or less cone-shaped with straight or curved sides, and a flat or pointed spire. They easily compensate the rather uniform shape by fantastic patterns and colours. The shell aperture is always a thin slit, parallel to the side of the shell, and juvenile and adult specimens have the same shape.

Cones are active hunters, killing prey with a venomous dart. The venom is a neurotoxin - it blocks the function of nerves - and humans are reported to have died from the sting of some large species. Live cones should be treated with caution, and their sting is certainly painful, but the popular impression of any cone sting causing immediate death is false. There are probably less than a dozen verifiable deaths of humans due to cone stings, though thousands of accounts of severe pain, numbing of muscles, etc.

There are over 300 extant species of cones, most of which live in the tropics, though a few are temperate or live in depths below 100 meter. They often live on or in sandy bottoms, hiding during day time, hunting by night.