Nautilus

Sunken chains and a current running backwards define Nautilus, a Unique aura added in Era 1 at 1 in 70,000. With no biome bonus, that is about 70,000 rolls at 1x luck or 7,000 with 10x. UnworldlyDice is the creator, and its in-game line is a small shout resounding from the abyss.

The Sol's RNG Wiki describes a cobalt chain that reaches the middle of the torso, smaller chains crossing the chest and wrapping the forehead and neck, and a large chain behind the player that seems to hold in place an ocean current moving the wrong way under their feet. Oceanic gas, bubbles and glowing dots flow upward from the floor, and a cobalt light shines down from an angle. The cutscene is a bluish-purple star on black with a dropbeat, expanding until blue edges reveal the aura.

Crafting gives it some value. The wiki's table shows it listed in the recipes for items such as the Aqua Device, the Gravitational Device and the Poseidon Godly Potion, along with others, so it is a common mid-tier ingredient. Its mutation is Nautilus : Lost, a Mythic version.