Here is the full list of all 18 CLeM achievements worth 1,000 gamerscore.
You've delivered a butterfly.
You've delivered a snail.
You've delivered a spider.
You've delivered a beetle.
You've delivered a firefly.
You've found the Lens of Truth.
You've secured the Runic Key.
You've got the Teleport Charm.
You've got Marvin the Marble.
You've got the Hat of Memories.
You've become a container like all the others.
You've liberated Clem.
You've found Martin.
You've found the flyer for Sandro's camps.
You've opened a complex lock at the first attempt.
You've used all of the teleportation circles.
You've discovered a memory at the first attempt.
You've filled your notebook with all the possible notes.