Fallstreak holes are natural phenomena
that often get mistaken for UFOs. These
‘hole punch clouds’ occur when water
droplets inside a cloud freeze and fall
beneath it, creating a large gap that
looks like a perfect hiding place for
a flying saucer.
The rarity of fallstreak holes is what tends to throw people.
That paired with the tendency to look at anything in the sky and cry ‘UFO!’ is the perfect makings of a false alien alarm.
Sometimes these clouds have little rainbows inside.
Scientists have made bouncy bones.
A new ‘ink’ that combines a mineral
from bones with a binding polymer
can be used to 3D print elastic bone
replacements. Because they are not
brittle, the implants can be shaped
as needed, and they become natural
bone after being placed in the body. Source