repepo, This fluid, seemingly at rest initially, turns out to be convecting as revealed by a #timelapse movie. #Evaporation cools the fluid at the surface, which makes it a bit heavier than the fluid below, thus #convection ensues, very slowly!
This fluid is #rheoscopic, easy to make at home using shaving cream.
Here's the recipe:
https://pubs.aip.org/aip/pof/article/30/8/087103/938850/Rheoscopic-fluids-in-a-post-Kalliroscope-world