Author 'Fifie34' (Id 104078 ) : Two little urchins, lost on the sand, my little son came to fish. When it comes to Sete is one of his favorite distractions ... but it does not consume! sea urchin, sea hedgehog sea chestnuts is a marine organism bearing spines. It may be brown, black, purple, green, white, red, multicolor. I confess to have never have seen other than brown, black or purple!