speakers ? amp ?

[nickid]

Need I help with my speaker set up.
search high and low for my amp and didn't find one but connecting and disconnecting the cable behind head unit I new the rear speakers were getting powered by something.
I decided to take the rear speakers off the shelf and found they both have extra components on the bottom of them that must be enhancing the power.
is this right? and can I replace them with other speakers and add the components to enhance them? or should I rip it all out and replace with the boss am set up