What is this SMD component
It is a Polyfuse- a kind of self-resetting current limiting device.  There are a few different names for them. Here is a datasheet. 



As far as names go, here is Wikipedia's take on it: 


  These devices are sold by different companies under various trademarks, including PolySwitch (TE Connectivity), Semifuse (ATC Semitec), "Fuzetec" (Fuzetec Technology), Polyfuse (Littelfuse) and Multifuse (Bourns, Inc.).[4] PolySwitch is the earliest product of this type, having been invented at Raychem Corporation (now TE Connectivity) and introduced in the early 1980s. Due to common availability, electronics engineers and technicians often refer to this device as a "polyswitch", in the generic sense, regardless of actual brand.