What is the black powder in side this heater?

I bought a heater for my turtles tank, http://www.petsmart.com/product/index.js鈥?/a> and long story short it exploded and it left a black powder everywhere. This black powder was already in it when I bought it.... is the powder dangerous?What is the black powder in side this heater?
Oxidized metal powder perhaps. No matter what, It's some sort of powder, probably metallic, from in the heater and should be cleaned out. No telling what metal it would be and how it may affect the water.What is the black powder in side this heater?
If you're not sure what the substance is, the best bet is to assume it's toxic and act accordingly.

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