Identifying SMT element 331K
If this were a capacitor, I'd say by the shape and size that it have to be tantalum. However, tantalum caps are polarized, and this device is not. Ergo, not likely a cap.

The triangular marking at the top of the device resembles the Epcos logo:



A quick check of Epcos shows me that they have a line of SM inductors which closely resemble your part, in both shape and markings.



This data sheet says that the line 331K represents the inductance and the bottom line is a date code.

This note explains the code in more detail: K is a tolerance code (+/- 10%), and depending on the size of the part, the inductance is in either microhenries or nanohenries. I don't think your part is actually 330 microhenries given its size.

I think you have a 330nH EPCOS SM inductor. QED