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