Here is the full list of all 32 Another Crab's Treasure achievements.
Try on every shell in the game.
Get your shell back.
Defeated Firth.
Learn all adaptations.
Fully upgrade Kril's fork.
Shoot a crab with a gun.
Find a certain hero's helmet.
Defeated the Curdled Carbonara Connoisseur.
Defeated Praya Dubia.
Defeated Camtscha (For real.)
Defeated Camtscha.
Defeated the Consortium.
Unlock all skills on the Path of The Hermit.
Defeated Inkerton.
Defeated Petroch.
Defeated Roland.
Defeated Voltai.
Unlock all skills on the Path of The True Crab.
Defeated Topoda.
Defeated Pagurus.
Unlock all skills on the Path of The Predator.
Defeated the Scuttling Sludge Steamroller.
Defeated the Ceviche Sisters.
Defeated Heikea.
Defeated the Diseased Lichenthrope.
Start the treasure hunt.
Purchase some insurance.
Fall off a cliff.
Defeated Magista.
Defeated a miniboss.
Defeated Nephro.
Defeated the Royal Shellsplitter.