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