Neptune's Shell

Merfolk aquatic form and boundless swimming

Dropped by Creature from the Deep during the Solar Eclipse with a 2% chance in Classic mode, rising to 3.96% in Expert and Master modes. When submerged in water, honey, or shimmer, the accessory transforms the player into a Merfolk. This transformation removes liquid movement penalties, grants infinite underwater breathing, and enables free swimming mobility in any direction, effectively negating drowning hazards.

Deep-sea exploration and lunar shell synthesis

Neptune's Shell removes aquatic hazards during deep ocean trench exploration or flooded cavern mining expeditions. At a Tinkerer's Workshop, it combines with the Moon Charm to forge the Moon Shell, which later crafts into the Celestial Shell for ultimate combat transformations. Modifiers applied by reforging remain active both in terrestrial combat and during Merfolk transformation. Reforging to Warding or Menacing ensures consistent utility throughout diverse aquatic challenges across all world depths.

Trivia

• In early versions of Terraria, Neptune's Shell was crafted using Souls of Fright rather than dropping from eclipse monsters.
• The Merfolk transformation activates immediately upon entering water or honey once submerged past torso height.