Another unidentified component
The most likely ID for that component is as a surface mount capacitor. There are two possible types:


Could be a capacitor with a high uF value. In that case it would likely be a multi layer ceramic capacitor (MLCC). The body material would look more like a ceramic material.
Could be a very high voltage SMT capacitor. Some types have a body material that provides better dielectric properties than standard ceramic capacitors and could appear to be more of a plastic or poly material. The large body size lends itself the clearance needed between high voltage circuits. At the same time it may very well have a value in the nF or pF range.