Ari momiri, the Greatening ritual, is performed by priests of the Vopa religion to induce mutation in its worshippers. It is often performed in gatherings and small crowds of people witnessing the mutation of another. These transformations can take a long time, and while uncomfortable they aren't usually painful.
The original Ari momiri, or Greatening, began when Sumiga first demonstrated the wormstone on their child, Lope. After Sumiga wrote the Parasoza, Lope was the first to read hir father's visions. Sumiga explained to Lope the risks of letting the wormstone mutations go unchecked: it might be possible for Pemija's children to render their host bodies useless without being able to rely on their astral bodies. The physical bodies of the Yalisi people needed to function enough that they could spread the word of their goddess.
When Sumiga asked Lope if they could use hir as a demonstration, to purposefully mutate their body to add a portion of astral body in theirs, ze said yes.
The Greatening ceremony happened near the exposed wormstone vein and had approximately 100 people in attendance. The audience encircled Sumiga and Lope, both standing on a singular raised platform.
To silence the babbling crowd, Lope raised hir hand into the air. Ze held aloft a handful of white fabric. Sumiga, much taller, stood behind hir and bellowed.
"See the power of the moon! Watch hir hand!"
Sumiga took the cloth away and Lope clutched the bare wormstone tightly in their palm. The crowd paused, uncertain what they were supposed to see. To the furthest people, there was nothing happening, the changes were too small. Onlookers in the nearest rows watched as Lope slowly grew another finger out of the back of hir hand. Sumiga then took the wormstone back and wrapped it in the white cloth.
"Look at hir hand. This is the work of Pemija."
Sumiga picked Lope up and carried hir onto their shoulders to make it easier for the throng to see the incorrect silhouette of hir hand against the blue sky.
Every Greatening ceremony is done in the same way to prove one's devotion to Pemija, just as Lope did.
Vubopas, priests, require small pieces of wormstone. They are kept on their person in vessels called imozi or obexu. The most necessary part of the ritual is the contact of bare skin with the wormstone, so even simple containers are effective in preventing mutation outside of the ritual.
A vubopa begins a su moti, a show, and gathers a crowd of between 20 to 1000 people, depending on the vubopa's magical strength. These participants are witnesses to the proof of Pemija's power, and they also become more in tune with Pemija herself as they gave watchfully from afar.
Greatening ceremonies are performed by su vubopa, especially ones that live and work in the capital of Yalisi, where more complicated and holy rituals are completed by the Mope Vubopa. New pilgrims come to demonstrate their commitment to Pemija often, but local su vubopa will perform Greatening ceremonies in the convert's own community. While congregations do grow, it is often in small spurts when a vubopa encounters a new community to proselytize to.
Members of the Libo sect, who do not agree with letting the astral children over to this world, are notable for not participating in su moti or Greatening ceremonies in general.