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