I don't believe they sting. I've been wrong before though.
I do know for a fact that they have a potent chemical warfare defense though. Their slime is loaded with toxins. Enough to kill a medium sized animal.
The toxin referenced above is not normally found in Zooanthids. Palytoxin can be associated with Palythoa although it's quite rare. That doesn't mean Palythoa are harmless without the Palytoxin, they have many other lethal toxins.
Please wear gloves and treat the water that you propogate them in as toxic.
Bang
PS - I'm pretty sure the Carbon chain is 129 atoms long.