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