To be fair, if you run your finger right now across a petri dish and let it culture it will look almost the same. I think the power of this image is that when you don't sanitize your mask every few hours (and most people don't), your mask will act like a petri dish and this is what happens inside your mask. Except, you won't usually see it because "designer" masks are multi-colored and the bacteria can grow all around the threads. It'a actually more harmful to someone if they wear these things and don't use clean ones every few hours.