User blog comment:Xilinoc/Ch. 631 - friend/@comment-8669536-20150618120459/@comment-8669536-20150619002450

If they are souls the question is "How did they become souls?" They could have been born as souls, but that seems kind of unlikely considering this chapter. If they were alive I doubt they would have died, so I would have to assume they used some kind of Reishi-conversion technique. They also would have needed something like that to enter Soul Society in the first place. But then does being made of Reishi/being a soul not by death guarantee a prolonged life?