MAMMATUS clouds are most often associated with the anvil cloud & severe thunderstorms. They often extend from the base of a cumulonimbus but may also be found under altocumulus, altostratus, stratocumulus, & cirrus clouds as well as volcanic ash clouds^
So crazy this happens! They are called frost flowers, a strange phenomenon where frost grows from imperfections in the surface ice amid extreme sub-zero temperatures nearing or forming spiky structures that have been found to house microorganisms.
Six fossils of salamanders were found embedded in volcanic ash in an ancient lake bed in western Liaoning Province, China. Photo: Mick Ellison, American Museum of Natural History/Proceedings of the National Academy of Sciences Posted on March 2012