Bismuth.
Typically, bismuth looks like this:

(It looks a bit like a big piece of meat wrapped in foil, doesn’t it?)
But under certain conditions, it looks like this:

Sensational, right?

A perfect crystalline structure.
It should be noted that bismuth is toxic and should not be handled frequently.
There are several curious facts about bismuth:
Bismuth-209 (the most common isotope) is radioactive, but it has one of the longest half-lives ever calculated: 1.9 x 10¹⁹ years, or about a billion times the age of the Universe. Pretty impressive, right?
Bismuth is the strongest naturally occurring diamagnetic element. Diamagnetic materials, when exposed to magnetic fields, are repelled rather than attracted . In other words: when placed on a sufficiently strong magnet, bismuth levitates.
Bismuth is relatively non-toxic for a heavy metal. Its periodic table neighbors, polonium, antimony, and lead, are super toxic , but bismuth is tolerable (not to be confused with completely harmless). Bismuth is even being studied as a replacement for lead in some specific applications.
Most people have ingested some amount of bismuth at some point in their lives. One of the ingredients in Pepto-Bismol is bismuth subsalicylate. For those unfamiliar, it’s an acid-reducing medication used to treat temporary stomach or gastrointestinal upsets and discomforts, such as heartburn and nausea.
Bismuth is pretty, but Praseodymium is just plain weird..
