hard, green, and quite compact
SOLVED: mystery number 2
Possibly another Echeveria. I am not all that sure though. Because there are a lot of plants out there that have similarities. Like graptopetalum(spelling might be majorly wrong), and many others that my brain connot spell at the moment.
Does it produce "babies" around itself? Maybe Sempervivum aka Hens and Chicks? Just a guess.