Spotted something(not sure if it fits in this section)

[Diabolic]

This is on my front passenger wheel and I'm not sure what to make of it. Not being very mechanically literate I decided to touch it, and it seems like grease? didn't smell of anything either, so not oil?

Can anyone identify what it might be?

[Surge]

Seems like you ran over something.

Either that or maybe your brake fluid is leaking.

Either way cleaning it may help identify where it's coming from.