I took the photos below while photographing only ordinary drops of pure, clean water falling in front of a black featureless background. On this day among other interesting results I got an orb motif consisting of two holes at the bottom of an orb. The motif occurred more than 1000 times, persisting through hundreds of consecutive photos. Below are some examples.
At the 45 second mark in the video below, you can see several video clips of my camera viewfinder as I photographed exactly this pattern.