I came across these a little while ago and bought them this afternoon:

I live in Nantes, France, and as far as I can tell these are only available in Brittany. I've tried the "marine" flavour; they're actually not too bad. They taste very slightly like raw oysters and a lot like plain salted chips.
I haven't tried the salted butter caramel ones yet... To be honest, I'm a little bit scared of them!