Astatine

Astat is the rarest naturally occurring element on earth. Any given moment there are only a few grams – as a decay product of uranium. The name comes ancient Greek meaning "unstable", because even its most stable isotope has a half-life of only a few hours. Because of its high radioactivity it can only be produced and examined in tiny amounts. Therefore there are no photos of this element nor can chemical experiments be conducted with it.

Nobody has seen the monster Asta Asta yet. Some believe it is ony a myth or a phantom.