Here is the full list of all 25 Creature in the Well achievements.
Heal a total of 1,000 health absorbed from anomaly balls
Find Phillip's prototype
Find all capes
Fully upgrade the BOT-Core
Find all of Danielle's tools
Find the scavenger's hidden stash
Find all the lore
Save Mirage from the sandstorm
Enter the Creature's well
Hit 20 bumpers with one shot
Charge 7 orbs at once
Unlock the Weather Control Monolith
Destroy 100 drones using EMPs
Generate a total of 2,000,000 power
Activate the Power Reserves
Help Roger mop the floor
Let's play
Try to escape the sandstorm
Unlock the Support Monoliths
Find a secret charge tool
Upgrade your BOT-Core
Find a secret strike tool
Get thrown out of the machine
Generate 1,000 power in one hit
Open the temple