The Daughter is the name used by the Axum for an object that impacted Proteus in the distant past. The event greatly impacted the Axum, who abandoned the Karakorum region for five-hundred years in the wake of the impact, taking refuge in deep waters, an event that would come to be known as the "Zero Year".
The Axum logogram used to represent The Daughter is translated as "comet".
Overview
Following the impact of The Daughter, the Axum began to use the event as a dating system, using "pi" (post impact) as their calendar years.
The impact of The Daughter is known to have destroyed the original telescope of the Observatory built by the Axum Ardhiacs. The Observatory was later rebuilt by Magi and Vepherds in the year 500pi. It is implied that The Daughter's impact may by a large reason for the present lack of shallow water kelp species.
As the current Observatory was built in 500pi, and according to the databank entry is around 1,000 years old it can be estimated that the Daughter fell approximately 1,500 years ago.
Axum Glyphs
Two glyphs make reference to events surrounding The Daughter.
Observatory Sign 2 — The Daughter
Location: Axum Observatory

Sequence: comet · Axum · deep · technology · see · death
After the zero year, when the Daughter fell from space, all Axum fled to deep water. The telescope was destroyed.
Observatory Sign 3 — Return
Location: Axum Observatory

Sequence: animal · help · Axum · technology · see · space
In the year 500 pi, brave magi and vepherds returned to Karakorum. They rebuilt this observatory to study the Erratic Messenger.
Trivia
- A track on the Subnautica 2 Original Soundtrack is named "When the Daughter Fell"