[latebind (OP)]

What is the rarest element in the universe?

How much of it is there? (Guess if you don;t know pls!)

[Ron Hughes]

Element 115.

[Shadec]

I would say the last few on the PT, as Ron pointed out. These don't really appear in nature, they're made by slamming atoms into each other,  so this wouldn't be too common without scientists manipulating things with accelerators and whatnot!
so the ones on the bottom row (not the Actinides and Lactinides) the actual lowest row. These atoms are extremely unstable, especially the larger (the larger the atomic number, the larger the atom), which last only for miniscule amounts of time