Mollusk Whistle

The Mollusk Whistle is a mount-summoning item that summons a rideable Flamingo mount. It can be purchased from the Zoologist for after 25% of the Bestiary have been unlocked.

The mount allows players to float in water, similar to using an Inner Tube, and dive by holding. The mount bobs to the surface when the key is released, and if deep enough, the player will launch out of the water into the air. This feature no longer functions while wearing Neptune's Shell or any effect that turns the player into a Merfolk. The flamingo will run unhindered underwater while the player has this buff.

Trivia

 * The buff tooltip is a portmanteau of the words "flamingo" and "go", repeated multiple times to form a command.