Don't have much to add except a few observations.

A. Osiris needs a backbone to stand. There's always the exhortation to put one's back into it. As a geyser Osiris was of little use with no backbone.

B. At the very bottom can be seen what appear to probably be alternating djeds and blood of Isis's. These are male and female, ying and yang, a water source and its distribution.

C&D. More "bubbly" Osiris.

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Man fears the pyramid, time fears man.