I did not know that yesterday!

As optometrist Kenton McWilliams of the MadSci Network explains, those blotchy shapes are formed by momentarily stunned bioluminescent microbes who live within your eyelid. Kidding! They're actually the result of the light-sensitive rods and cones in your retina becoming momentarily overwhelmed by an immediate influx of light. As you may recall from your high school anatomy class, the rods register lightness and darkness, while the cones distinguish color. The rods vastly outnumber the cones; there are roughly 120 million rods to 7 million cones.

The cones are probably responsible for the strange colors involved, as they are concentrated in the central part of the eye. According to the American Optometric Association, your rods become more active in darker environments -- it can take up to 25 minutes for your eyes to become fully "acclimated" in a dark room.

If you're seeing spots without the benefit of a flash or a sudden change in ambient light, you may want to get to an eye doctor. You may also be interested to know that those strange shapes you occasionally see floating across your field of vision are known as "floaters," and are actually tiny clumps of cells floating inside the vitreous, or the clear jelly that fills your eye.