If Prickly is NOT a sea urchin, then I'm the Emperor Penguin of Africa.
Seriously, Pricky is a sea urchin. That's what I think anyway, doesn't look like he could be anything else.
I remember when I was young and playing Super Mario World, Prickly scared the daylights out of me. I felt like I was gonna have a heart attack in the one area where you go down a pipe, which leads you to an area where you're forced to swim against the current while a Prickly quickly approaches.
Which is why the 'A' button was invented ;)