Old tubos make for awesome humidifiers, I agree. But if I can salvage Rondos in addition to the tubemidifiers, why not?
You are right, Credo makes them in two parts, likely glued.
I have tried to pry them open, twist them open, tried to tap them with a screwdriver at their junction, and it seems it will break before splitting appart.
There must be a trick. But I have not found it so far.