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.
Learn all adaptations.
Shoot a crab with a gun.
Defeated the Curdled Carbonara Connoisseur.
Defeated Petroch.
Defeated Roland.
Unlock all skills on the Path of The Hermit.
Defeated Voltai.
Unlock all skills on the Path of The Predator.
Defeated the Ceviche Sisters.
Defeated the Scuttling Sludge Steamroller.
Unlock all skills on the Path of The True Crab.
Defeated Pagurus.
Defeated the Consortium.
Purchase some insurance.
Defeated Topoda.
Defeated Heikea.
Fall off a cliff.
Defeated the Diseased Lichenthrope.
Start the treasure hunt.
Defeated Magista.
Defeated a miniboss.
Defeated the Royal Shellsplitter.
Defeated Nephro.