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