The letter ℘: name and origin? (2017)

In the same Unicode block is "2129 ℩ TURNED GREEK SMALL LETTER IOTA" with explanation "unique element fulfilling a description (logic)".

That seems a ridiculous choice for a symbol — turning one of the most symmetrical letters upside down!

Background: https://philosophy.stackexchange.com/questions/51563/what-is...

It could be motivated by the fact that Russell and Whitehead needed a symbol for printing that the printer had in his type case but could not be confused with anything else. Taking a iota and simply turning it upside down would then be a rather ingenious idea. But that is just my speculation ...