We're so used to seeing light, white fluffy clouds; or alternatively heavy gray ones; that it now creeps us out a little when we see anything that deviates from that norm. Take these disc shaped clouds for example; they look like they've been made by hand and spun into shape. Also, is it us, or do they look like they're riding on the back of a dolphin?
In the past, lens or disc shaped clouds have been responsible for false reports of UFOs, and you can understand why; to the untrained eye, and on a dark night, they might look like flying saucers. Here's the science; a lens shaped cloud forms when a normal crowd blows across the top of a mountain, thus disrupting the flow of air within the cloud. Moister, stable air rushes into the gap, and then condenses to form a flat cloud, which wind then turns into this distinctive shape.