I loved the picture of the living sea urchin, usually you just see the empty mineral shell. Bizarrely they have 5fold symmetry. They’re Echinoderms [from the Greek for spine] and inhabit many different marine habitats. Painful if you brush against the spines though!
I’ve used several strands of wool, mohair, and cotton, mostly from charity shops or from leftovers. It’s knitted on 6mm needles in the round, and I stuffed it before finishing off. I felted it so it shrank and then brushed it to show the mohair ‘halo’ imitating the spines.
It is around 12cm