Can anyone tell me what this boat seat part is called?

It appears to be rubber and is screwed to the bottom of my boat seats........2 per seat.

Thanks

I have never seen something like that on a boat seat. It looks like a shock mount that we used on our equipment on to help reduce the noise transmission to to the hull & to reduced the shock effect on the equipment upon being depth charged.

Bumper?

How bout a wider angle shot so we can see more of the seat and how this is used.  Also what kind of boat is this on?

Garelick active seat suspension system.  I have one on my seat also and had to replace those rubber bumpers.  The newer style are better.http://www.garelick.com/Active-Seat-Suspension-Systems

 

I cant tell for sure but I think your missing pieces.

Thanks everyone........Siebert hit it on the head. They are called foam shocks.