props to you stoned fish. i've never heard of heaters burried in the substrate. i always thought you needed water to swirl around the heater to evenly heat the tank. but if it works, then at least you don't see them.
as for the dat, he's getting punked by somebody, if he's staying there long enough to get burned.
although there is an animal(i forget maybe frogs) if you put in cold water and turn to knob to boil, it doesn't even realize its getting cooked.
in short, get a gaurd.