The purists will probably prefer to shoot shells in situ (as the shot here), and that is fine. But sometimes it is good to take the lazy option and buy some to shoot in the comfort of your house, hotel room or beach hut. Not only that but it means you can buy some exotic, non-native specimens to shoot too.
You normal DSLR outfit would suit perfectly well, especially if you have the accessories to get you in close to fill the frame. If not, explore the subject with a digital compact with a good close-focusing mode.
If you are at home, you can even press the flatbed scanner into service. In fact, the flatbed scanner is a very good capturing device if you want to try something different. I recall meeting a photographer a while ago who went round scanning plants in situ in his garden using a laptop and the scanner connected to a very long mains extension lead.
Assuming you are away on holiday and therefore away from base, you are probably limited to what lighting accessories you might have available. However, that is fine because sunlight is perfectly good and you can always improvise with props, reflectors and so on. For example, a coloured towel can make a for a background and a white one would work well as a reflector. A little ingenuity can go a long way.
At home, try using domestic lighting, doing a custom white-balance first to ensure a neutral result. Or just shoot and accept any colour cast as creative.