These beautifully colourful creatures are isopods known as Armadillidium gestroi – a species which in the wild can be found in southern France and Italy.
This is certainly a strikingly beautiful species of isopod and a firm favourite with all the children they meet!
Like all arthropods, isopods have to moult their exoskeleton regularly during their life cycle. Unlike other arthropods, however, isopods do it in two distinct sections rather than in one piece like most other arthropods! They moult the posterior (back) half of their body first, then within a couple of days they moult the anterior or front half of the body. Here is one I caught shortly after moulting its front half!
You can see that the front half of the body (slightly hidden underneath the removed exoskeleton) is a slightly paler colour immediately after moulting as it softer than usual. Within a couple of days the body hardens up and will be back to its normal colouration! It sure is a fascinating process to witness.