Here is the full list of all 32 Another Crab's Treasure achievements.
Fully upgrade Kril's fork.
Defeated the Consortium.
Learn all adaptations.
Defeated the Curdled Carbonara Connoisseur.
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.
Unlock all skills on the Path of The Hermit.
Defeated Petroch.
Defeated Roland.
Defeated Voltai.
Unlock all skills on the Path of The True Crab.
Defeated Pagurus.
Defeated the Ceviche Sisters.
Unlock all skills on the Path of The Predator.
Defeated the Scuttling Sludge Steamroller.
Defeated the Royal Shellsplitter.
Defeated Topoda.
Defeated Heikea.
Defeated the Diseased Lichenthrope.
Start the treasure hunt.
Purchase some insurance.
Fall off a cliff.
Defeated Magista.
Defeated a miniboss.
Defeated Nephro.