15 feet is enormous. I have personally seen them that large in diameter and about 8 feet long. They are easy to notice because they let you know when you are near. Its a shame they killed it, but if some kid ran into it, it would either kill them with the bite or cause them to loose a limb depending on the location of the bite. I do not eat them, but I know many do. At worst, they could have put it in the JAX zoo because that would have to be the largest one seen to date.