Best way to revive a vintage soap puck

Hi there,



I've collected a few vintage soap pucks, and am looking for guidance as to how I might get them going. They appear pretty musty on top, but I'm curious if I should test-lather and see if I can get down to the goodness below!



Any strategies or suggestions would be welcome! This is my first time attempting such a task, so I want to learn well!



Thanks in advance!



-Alex