Click the green flag and watch corals grow.
I modified @crkcity's lovely original project very slightly, simply increasing the falling speed and adding the backdrop. (The original project has been updated and is now similar to this, but with a beautiful original painting as a backdrop instead of the Scratch library image I have used, so go check that out!) I have actually remixed a similar project earlier - @SussieGD's Snow Simulator: https://scratch.mit.edu/projects/398236306 And apparently @Brontosplachna had this idea long before us: https://scratch.mit.edu/projects/25769123