Can I bury my Aqueon Flat Heater?

Hello, I'm curious if anyone knows, can I bury my Aqueon Flat Heater under sand in my 5 gallon? It's not glass, it's one of the flat heaters about the size of a deck of cards, a little bigger than that. It looks like it's all black plastic.

Right now it's sitting on the bottom of a bare bottom tank that I want to add sand and such to. Since it's not glass could I? It's being a little too efficient as well, keeping the water 80-84, think that's ok? It's for a betta, and It usually hovers around 80, but early morning it's 83ish.

Thanks!