What is this Circuit component?

What is the circuit component covered with a hard black compound? It is circular domed and I think it might be a microcontroller(?). I find it in some cheap toys etc.?

Its a very cheap way of mounting complex chips, if you have the volume of production called "Chip On Board",or flipchip. The chip is bonded to the board by special solder balls which are reflowed during manufacture.

So it isn't "A" chip, it could be anything.

Yeah, it really could be anything. Usually sometihng like a simple microchip.