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