I found this rock in my front yard. At first I thought it was some kind of sea shell, but looking closely it seems like a marine fossil. A strange formation of what looked like some kind of sea shells. Anyone know what kind of rock is this? If it is a fossil, is it a marine one???

Underneath ….It looks like many broken sea shells.

Update: After searching online, now we know what it is: Petrified Goniastrea favulus, honeycomb coral.