The description and picture for Aqueous Essence

Aqueous Essence is used to allow the player to play as a Naiad. Naiads are great for Rangers, Dragoons and Aquamancers because of the increased damage with piercing weapons and water based attacks. Aqueous Essence can be gotten from the following monsters (or bought from other players for around 800k-1million g.)

Zorbi Frogger drops it at 0.01%
Zorbi Minor drops it at 0.2%
Zorbi Ninja drops it at 0.1%
Champ drops it at 0.9%
Zorbi Brute drops it at 0.1%