I got stuck by a Diadema setosum (orange 'eye'-not an eye ;) ) when I picked mine up. It hurt like a mother for almost an hour, then slowly strated to subside.
Tips on urchin poisoning. Don't try to pull the fragment out of the wound. the barbed end will not come out and you will make matters worse. The toxin acts as soon as it enters your skin (nothing you can do about that). Typically, the affected area quits hurting after a few hours. It may still remain painful to the touch, though, just not the same pain you got from the toxin. The blue-black coloration can remain in the skin for weeks. Mine was around for at least a week, but quit hurting after about an hour and was no longer tender after about 2 days. If I hit right on the spot, it would be tender, but no real pain several days later. Sometimes the fragment will get encapsulated (and usually dissolves in the skin). If it is still very painful and the lasting pain wasn't caused by you trying to get the spine out, I'd definitely go in and have someone look at it. If you've been messing with and possily made it worse, you still might want to go in, but it will most likely be a waiting game. Mine dissolved in my skin with no further action from me (other than icing it). Your's may need to be removed, but let's hope it dissolves.
