Here is the full list of all 12 Escargot achievements.
Complete World 1
Complete World 2
Complete World 3
Complete World 4
Obtain 10 Diamond Medals
Obtain 20 Diamond Medals
Obtain 30 Diamond Medals
Obtain All (40) Diamond Medals
Obtain 25 Golden Shells
Obtain 50 Golden Shells
Obtain All (100) Golden Shells