This stuff is on the side of my engine by the belt and water pump. Any idea why it's there or how bad it can get/what it can cause?

 

whats it feel like? will it rub off? honestly kinda hard to tell from the pics on the texture but if it rubs off could just be ____ from the road coming up into the engine bay

i know here in NY my engine is covered in ____ from the road salt and sand

 

Its rough and the aluminum has grooves in it. I haven't tried rubbing it off since the engine was hot. I'm in Texas and our weather isn't as extreme in the winter so I don't have the slightest idea what could have caused it.