Underwater Sahuagin temple

This temple was found in the Underground Lake deep with Greg's Mine.
This ancient temple was of sahuagin construction and seemed to be almost completely destroyed, probably pre-shattering by a natural disaster.
The party found an ancient fresco depicting a large shark-like humanoid being worshipped as well as the remnants of a statue from Magron, 3rd born of Sekolah, the cold hunger . In an antechamber, they discovered the remains of a dig, with at the bottom a dark marble onyx casket engraved with runes in aquan. The casket was pried open and broken.
The runes read "Here rests Magron, may he rise once more a draw blood from our enemies."
Whilst prying ruby eyes from a shark engraving on the plaque of the statue, a tile slid open and released a shark carcass (that later animated into a Zombie Giant Shark. Rummaging around in the remains fed to the shark, they found the Ring of Renewal.