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