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