Conversation so far:
What role do priests play in Mandaeism?
There is a strict division between Mandaean laity and the priests.
What are the three grades of priesthood in Mandaeism?
There are three grades of priesthood in Mandaeism: the tarmidia disciples, the ganzibria treasurers and the rišamma leader of the people.
How does one become a priest in Mandaeism?
Any ganzeḇrā who baptizes seven or more ganzeḇrānā may qualify for the office of rišamma, though the Mandaean community has yet to rally as a whole behind any single candidate.
What are some differences between priests and laymen in Mandaeism?
There is a strict division between Mandaean laity and the priests.
Why is there division between priests and laymen in Mandaeism?
The ignorant or semi-ignorant laity are called 'Mandaeans', Mandaiia—'gnostics.' When a man becomes a priest he leaves 'Mandaeanism' and enters tarmiduta, 'priesthood.'

Question: Is there any other interesting information regarding this topic?
Self-contained rewrite: Is there any other interesting information regarding Mandaeism aside from the division between priests and laymen?