Cusicesh the Protector is a massive spren that appears at the same time - seven forty-six every morning, without fail - from the inland sea within Iri. (The locals could use it to set their timepieces.) Some Iriali people worship it as a god. The display lasts only ten minutes.
It is sea-blue in color, translucent, and appears to throw out waves as it rises from the inland sea. As observed by Axies, it takes the shape of a large jet of water, its center of deepest blue, like the depths of the ocean, but the outer edges are a lighter shade.
It has formed a face, looking eastward. Directly toward the Origin. That face is shifting, bewilderingly quick. Different human faces appear on the end of its stumplike neck, one after another in blurred succession.
The faces changed so quickly that Axies couldn't tell whether any of them repeated. Some of the faces seemed male, others female.
This spren is judged to be at least a hundred feet; one of the largest Axies has ever seen. It is capable of sprouting four long arms, forming fingers and thumbs.
Once the spren's display was finished, Cusicesh retreated down into the bay, sending up phantom waves again.
Brandon has indicated that the Stormfather is a bit above both the Nightwatcher and Cusicesh. Further, that they are also a much bigger deal than something like one of the sapient spren, and that that's what Cusicesh is.
It has been questioned amongst fan communities whether Cusicesh is yet another of those unique spren that bonds exclusively to certain individuals, as does the Stormfather to a member of the Bondsmiths.
Is Cusicesh akin to a tardigrade?