This is how they do it in Africa , get a glass coke bottle or similar and tap the foot around the area where the spines are in, this hurts , but breaks up the spines.
Also anyone that has had em knows you can't pull 'em out intact as it is a waste of time!
Then after about 2 or 3 minutes of beating your foot get a fresh paw paw and rub it on the area anyway it works.
Or
Remove the spines that you receive from the urchin. This will hurt, but it is necessary in order for it to start the healing process. It is imperative that you take them out fast in order to reduce the pain and get most of the spine out.
Cover the affected area with vinegar once you get out of the water. Soak a lint-free towel in vinegar and hold it on there as long as possible.
Soak it in hot water for as hot as you can tolerate. It will ease the pain and help to relieve soreness on the following day. Put vinegar on it again.
When you go to bed, wrap the area that was stung with a lint-free towel, soaked in vinegar. Wrap the towel in plastic wrap and tape it so it stays on through the night.
You will not get the entire spine out, no matter how much you try. Do not dig into the skin with a pin or any type of needle.
The sting will hurt, but in the majority of cases, it is not necessary to seek medical attention! In some cases you may not even be able to bend your joint, if you were stung in that area. However, if you feel as though it is necessary, then do seek attention.
Sea urchins inject a small amount of venom when stinging, but the amount is negligible to cause any serious injury if you are only stung by one urchin.
The more you keep vinegar on the area that was stung the better off you will be.
The spines in your skin will dissolve on their own. Do not dig at them to get them out. It is completely normal to have them in your skin.
But it hurts like a bugger so wear booties.