What is this character? How to identify it? Came across this etching in a ABAC pattern as the A:



The more complicated ones were easier to identify, but this one is kind of tricky.

One guess was that it was the character for 今, but that doesn't check out because it would probably look more like this:



Any ideas what this is? How to go about identifying it?
The character is the Shuowen seal form of「克」.

「克」was originally a compound of「由」(a helmet, top part of「冑」) and a reduced form of「皮」(an animal being skinned for its hide, with the action being represented by the hand「又」;「又」is not present in the original forms of「克」):



Illustrative purposes only; this may not be strictly how the character changed over the years.

Compare: