Common House Leek – Sempervivum tectorum Linnaeus (l735.)
Just in case:
Sempervivum (Lat. = ’ever-living") since time immemorial was believed to be able to protect buildings from lightning and, hence, it was grown on roofs without any soil or other planting substrate.
Nowadays meeting the Common (and you know now why it was “common”) House Leek still cultivated like that provides a rare insight into the increasingly darker and darker abysses of disappearing worlds.
Produces exactly the same biologically active substances and commands the very same healing power for which the nowadays much-tooted Aloe vera is in vogue today