From Halopedia, the Halo wiki
Crellum was a village in the Reskolah region on Janjur Qom, the homeworld of the San'Shyuum. Crellum was a fishing community, located along the edge of a large lake near a jungle. The settlement was essentially just a double row of oval houses made of wood and plaster. Some of the houses were on stilts over the lake. The homes were built in an old-style that resembled the shape of an average San'Shyuum skull. The village's light sources were powered by the sun's energy during the day, which was gathered by plants on the roofing of each homestead. Garfren were domesticated in the village for meat, milk, and cheese.
The village was under the control of the Stoics. There were few young males in Crellum; most males were conscripted into the Stoics' military. When young males did arrive in the village, they often treated the females "barbarically". The village had essentially no military force. The large fish populations in the lake became scarce as males from the planet's capital city reduced their numbers by overfishing.
In around 850 BCE, a Covenant Eye spy probe was sent to Crellum from High Charity by the Ministry of Anticipatory Security. The Eye displayed a holographic message to certain fertile San'Shyuum females in the village. Eight females that viewed the message agreed to come to High Charity for breeding purposes. A Covenant expedition team, led by Mken 'Scre'ah'ben, the Prophet of Inner Conviction, was sent to the village on a mission to retrieve the females and return them to High Charity. Before coming to Crellum, the team entered the grotto of the Great Transition to retrieve a Forerunner Luminary. At the grotto, they engaged Stoic forces before escaping the area. The Stoics in the area began searching for other off-worlders. After meeting with the females that were aboard a domesticated ilpdor, named Erb, the group departed the village with the females.
Crellum is referred to as "Trellem" in Halo: Broken Circle (page 90, Google Play edition). This is likely just a misspelling, as Trellem is never mentioned again.
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