Watery Palace of the Ooze Behemoth: Level 5 Pearly Spiral of the Endless Hunger

From the introduction: Within the earth a shelled great creature one crawled. Long ago it died, but its shell remained. Above it, a Hidden Temple was built, and dungeons below it. Upon reaching the cavern that holds the shell they used the hulk of the great beast to aid them in reaching further into the ground, and the horrors below.