Finding the Trilobite puzzle - Get the Animal Ignot in the "Natural History Museum" level. Search the circular middle room with the "tree" object in the middle until you find a picture with trilobites on the wall. Shine your flashlight at it with the Animal power selected to start the puzzle.

Accomplish the indicated achievement to get the corresponding number of Gamerscore points:

Been There, Done That (100 points): Obtain all Awards in the Awards Room.
Flashback (20 points): Complete Tablet Tutorial at New York Museum of Natural History.
A New Threat (20 points): Escape Federal Archives.
Monkeyshines (30 points): Complete National Air and Space Museum: Able Chase.
Fine Art (30 points): Complete Washington Art Museum.
Natural Wonder (30 points): Complete National Museum of Natural History.
Final Frontier (30 points): Complete National Air and Space Museum: Hangar.
City Pass (40 points): Explore All Museums.
Morning Comes (50 points): Save the World.
In Orbit (10 points): Free Able from her Restraints.
With a Monkey Chaser (10 points): Navigate the Vending Machine.
Fossil Fuel (10 points): Complete the Trilobite Puzzle in the National Museum of Natural History.
Anubee (10 points): Complete Anubis Columns Puzzle.
Crown Jewels (10 points): Return the Hope Diamond.
Lady Lindy (10 points): Restore Power to Amelia Earhart's Plane.
Hey! Dum-dum! (10 points): Give the Gum to Stonehead.
The Light Touch (10 points): Tame all Animals.
Rotor Router (20 points): Complete the Autogyro Flight.
The Eagle Has Landed (20 points): Complete Lunar Lander sequence with at least Two Bars of Health Remaining.
Mudface (20 points): Repair all Broken Exhibits in Washington Art Museum.
Art Appreciation (30 points): Activate all Paintings Traps in the Washington Art Museum with the Flashlight.
Who's Got It All? (100 points): Collect 100% of Hidden Items.
Magnetic Personality (20 points): Acquire all "Museum Magnet" Collectibles.
Gone Postal (20 points): Acquire all "Postcard" Collectibles.
Wrench Wrangler (20 points): Acquire all "Wrench" Collectibles.
Fourth of July (20 points): Acquire all "Souvenir Document" Collectibles.
Picasso (20 points): Acquire all "Paint Tube" Collectibles.
Rexy's Favorite (20 points): Acquire all "Bone" Collectibles.
Toolbox Hero (20 points): Acquire all "Pilot's Wings" Collectibles.
Mint Condition (20 points): Acquire the Pressed Penny Collectible in New York Museum of Natural History.
Castle Me (20 points): Acquire the Pressed Penny Collectible in Smithsonian Castle.
Penny Pinch (20 points): Acquire the Pressed Penny Collectible in Lincoln Memorial.
Coin a Phrase (20 points): Acquire the Pressed Penny Collectible in Federal Archives.
Inflation (20 points): Acquire the Pressed Penny Collectible in National Air and Space Museum.
For Art's Sake (20 points): Acquire the Pressed Penny Collectible in Washington Art Museum.
No Quarter (20 points): Acquire the Pressed Penny Collectible in National Museum of Natural History.
Pressin' Yer Luck (100 points): Acquire the Pressed Penny Collectible in ALL Museums.