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