Moth eggs. It would be easier to have a guess at which moth if we could see the other side under a microscope, and knew your local moths, and If I were a Lepidopterist, which I am not!
They are incidentally not growing, but incubating. If you keep a sharp eye open, you might be able to see when they hatch. What to feed them would be a puzzle though. But if you guess right, you could support the caterpillars until they turn into something recognisable.
What often happens is for a moth to come to a lighted window or wall, and being too gormless and exhausted (as you and I also might be under analogous circumstances) to go back to seek out proper food to lay its eggs on, it just lets go and lays them where it happens to be. Good luck to the next generation.
Much like humans. At least she tried...
