What oil?

[cypgirl]

I have a large collection of cypraea/cowrie shells that I keep in plastic boxes covered with handkerchiefs. But I've been told that to keep them in the best condition and to make them look nice and shiny I should wipe them with oil. I'm having trouble finding mineral oil that doesn't have purfume added in it, does the purfume harm the shells over time? I live in the UK, please can someone direct me to a product I can buy to safely coat my shells with. Any oil that is not harmful to the cowries. Thanks a lot. (Please can you try to give me a link to the product)