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