Is it Grey or Gray?

If a child is to keep alive his inborn sense of wonder, he needs the companionship of at least one adult who can share it, rediscovering with him the joy, excitement and mystery of the world we live in.
-Rachel Louise Carson –


I’d like to give you a hint for this photo, but I can’t think of anything that won’t be a dead giveaway. So you are on your own. What is this a close up photo of?