The reason it's worth mentioning is that the true heat mats that animals are supposed to lay on often severely injure and kill iguanas. Iguanas need all their heat to come from above. They can't feel their bellies when they over-heat into a giant blister which turns into a heavy scab, and can burn their stomachs. That happened to one of mine very early on. He lived.
Zilla, dang them, have a heat mat package with a picture of an iguana on it. That misleads many people and the pet store clerks don't know squat.
Zilla refuses o budge.