Particle gallery
Moss, on Mona Lisa. Soft and close. It gives way under the pointer and grows back slowly.
About the particles
12 ways for the particles to behave. Some push away, some draw in, some keep to lines, and one follows the land. Pick one, then move the pointer through it; Shuffle picks one, and an image, for you.
Mona Lisa, Leonardo da Vinci, about 1503 to 1506. Public domain.
Try them on your own images, and change every setting.