Nah the soil I use is top notch, I have been reading up on mamms and there was some notes on rain getting trapped under the spines. I thought it was the size, it was about 30cm across, and a bit pot bound when I got it back.
I divided it this afternoon, it was rotted at the base so I have about fifteen plants drying out now, I just cut them above thr rot and the other tissue looks good.