Thaddeus and Rodmund Mung, also known as the Brothers Mung or the Mung Brothers, are a pair of brothers from Marielda who were stranded on an obsidian berg during The Quiet Year.
The Quiet Year
Because the boat made to sail the burning seas had to be periodically removed, the only way to mine the obsidian bergs was to leave workers there and come back for them later on. Thaddeus and Rodmund, who were rich enough to be involved with the boat but not rich enough to not get stuck with the shittiest job, were stranded when the boat was destroyed by Tamsyn and others from Canopy Row before it could come pick them up.
As they waited for rescue, they heard a hum and found the strange orb which had been thrown into the ocean after the plesiosaur's attack on Marielda. It appeared undamaged and they fished it out of the lava water.
After a while, seeing that they had not died from starvation or exposure, the brothers decided to try their luck by strapping their hands to the orb with belts and swimming to Marielda, where they emerged one night wet, naked, but unharmed, with their hands having fused to the orb. They made their way through the cracked section of the wall and went to Canopy Row, thinking that the rich folks had abandoned them.
The orb's healing properties "brought back hundreds from the brink of death" during the winter battles with Samot's forces, but at some point it was apparently lost.
Later endeavors
The brothers later founded Mung Quarry & Conveyance, an obsidian mining company they use as a front for smuggling.