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