Could be a Ricordea yuma but I cannot see the mouth very well. The other question though is how did it multiply as Yumas normally do do by a piece off the base splitting off and growing into a new yuma so if you now have a whole bunch how did they multiply?
Here is a pic of one having done so a while ago : you can see the Baby at the bottom of the one on the right Yuma ...
Based on splitting not a Yuma ... agree on Rhodactis too. Great that you now have 7 or 8 now, which is not all that slow as you indicated Looking good too.