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