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