“Tatoo” is derived from tatou, the French word for “armadillo.” And that’s what the design evokes. Rather than a single carapace, it comprises several polypropylene strips, which come into shape after the joints are clicked together:
And actually, the entire helmet is made of polypropylene, so that it’s readily recyclable. When you’re not wearing it, it can be packed flat for storage:
Now, folding helmets can be ingenious–for example, the Tatamat.
This one, however, is totally ridiculous, and neglects the way bike helmets actually work. It’s not simply that they’re padded–the padding inside a bike helmet is mostly for wearer comfort, rather than protection. Rather, helmets protect you because they’re monolithic and rigid–that allows the force of an impact to transmitted along their length, rather than directly into your head. They’re made of foam both to be lightweight and so that they can easily crack–just like a racecar, they’re meant to break-up upon impact, to further disperse kinetic energy.