How can I permenently preserve fruit?

A few days ago I found these awesome ice creams, they're basically just sorbet, but they're packaged in the halve of the fruit that goes with it's respective flavour. for example the pineapple sorbet is inside the hollowed out halve of the actual pineapple fruit. I bought like every flavour they had so I now have a lot of them, and they are a perfect size to be small bowls, for like earrings and junk. SO, how can I make it so that the fruit halves are completely sealed, hardened, bowl like and not rotted??? I was thinking shalack but I don't know if it would still rot. Any help would be appreciated!! Thanks!