I have looked at diatoms under a cheap microscope to diagnose an algae outbreak in my saltwater reef aquarium at home. There had to be thousands in my tiny sample. They had a red/pinkish hue that was really interesting to observe. After introduction of copepods and a UV sterilizer, the outbreak went away. These organisms are incredibly interesting along with other photosynthetic marine life.
I was rejected by the App Store a few months ago because I named my app {AppName}GPT for use of a "registered" trademark. I got through their review process with my first few versions, but on my third update they rejected. Ultimately, I decided on a name change and it's yielded better results for ASO anyways.