Entering water with this accessory equipped transforms the player into Merfolk form. While in this form, the breath meter will not display (nor will it decrease), therefore effectively preventing drowning. The player will be able to move freely in water.
If the Moon Shell is made invisible in the accessory slot, the character will not appear to change into a Werewolf or a Merfolk although the buff is still applied.
If equipped into a social slot, the werewolf form overrides the human form regardless of the time of day. However, this is only a visual appearance, and the player will receive no actual buffs or bonuses.
While the components of the Moon Shell sell for a combined 1050, the Moon Shell only sells for 8 (23.81% less).
The Moon Charm is rarer than Neptune's Shell despite having the same drop rate due to werewolves spawning in much lower numbers during a full moon than creatures of the deeps do during an eclipse. A Blood Moon will increase the Werewolf spawn rate. A naturally occurring full Blood Moon occurs an average of once in 72 days, during which time 3–4 eclipses can be expected even without Solar Tablets.