This is a yellow jelly fungus, also called witch’s butter – a name that makes sense because this image looks like something you might find bubbling in a witch’s cauldron. The name is a nod to the ...

“Double, double, toil and trouble; Fire burn, and cauldron bubble,” the agency said. “No, this isn’t a witches’ brew! These swirls are blue-green algae, or cyanobacteria.” The photo ...