There appear to be greenish hearts and bluish ones, though they are the same color. pic.twitter.com/NachmY6y37
— Akiyoshi Kitaoka (@AkiyoshiKitaoka) February 16, 2018
If the red lines go through the heart, it looks blue. But if the yellow lines go through it, it looks green. Enlarge the picture to see this better. It’s amazing how our eyes can be fooled.