Answer:
Sometimes black, sometimes white, I have veins but no blood
This thing runs but cannot walk, sometimes sings but never talks. Lacks arms, has hands; lacks a head but has a face.
Only one color, but not one size. Stuck at the bottom, yet easily flies. Present in sun, but not in rain. Doing no harm, and feeling no pain.
I am nothing really at all, Yet I am easily foundΝΎ Ignore me at your own peril, and you might end up crowned!
I can be short and sometimes hot. When displayed, I rarely impress.
Keep doing me to avoid lens dryness