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