This is more of a last ditch effort: *Disclaimer* please use your own judgment on this, I do not take any responsibility for you being harassed/handcuffed by the TSA/Police. It is always better to ask permission from the airline than ask for forgiveness from the TSA *Disclaimer*
If they wont let you take them on the plane because of liquid requirements you could always wrap them in a paper towel and have them in a bag of water ready to go. When you get to the airport and are about to go through security, pull the corals out (leave them wrapped in the paper towel) and put them all in a small ziplock bag to keep residual moisture in. I'm not sure where you are coming from, but if the flight is less than 12 hours I would think you will be ok. Remember this is more of a last ditch effort, better to do this than have the TSA throw them in the garbage....
Of course shipping in water would be the best, but I know of people who ship corals in paper towels so if the bag is punctured the coral stays moist until it is delivered. And they have had numerous bags puncture. what type of corals are these?
You could always ask when you get to the airport. And if possible putting them in checked luggage is probably best if you cant take them carry on in water