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