In each of Yooka-Laylee's worlds, you'll find a peculiar-looking device called the D.N.Ray, which is accompanied by the octapus-doctor known as Dr. Puzz.
Dr. Puzz will, each time, ask you to go and find a missing Mollycool to power her machine - and when you find it, turn you into a different transformation, like a plant, or a truck, which lets you solve some of the worlds' unique puzzles, find new Pagies, or unlock bosses.
If you need more help, then consult our Yooka-Laylee guide and walkthrough for finding Pagies and other collectibles.
Tribalstack Tropics Mollycool location, Dr Puzz, and Transformation
Dr Puzz location - Dr Puzz can be found on the far side of the central temple to the world's entrance, just to the right. You'll see her standing next to her D.N.Ray machine by a couple of mid-sized boulders in the grassy area.
Tribalstack Tropics Mollycool location - the Tribalstack Tropics Mollycool is located at the top of a tall pillar, quite near to Dr Puzz and the D.N.Ray itself.
To get there, you need to head to the middle level of the world's central temple. Make sure you've bought the Sonar Shot ability from Trouzer (also found in the temple), and use that to shoot the totem behind him and activate the moving platform that takes you to the middle level.
From there, head to the side that has the frozen berry plant, and hop onto the moving platform you'll see in the air nearby. Follow the platforms across to the pillar at the end of the trail - Quills help guide the way - and you'll find the Mollycool. Head back to the Dr Puzz for the transformation!
Transformation - Using the D.N.Ray to transform will turn you into a plant in Tribalstack Tropics. There are two benefits here: firstly, you can talk to any of the plants dotted around the world for some tips on nearby secrets.
Second, it lets you talk to a specific plant that gives you a Pagie for completing a task. The plant in question is located towards the back of the world, by the large face carved into the rock wall, further from the entrance than Dr Puzz and the Ray.
The plant in question is surrounded by other, smaller plants, or buds, you could say. The task is to fertilize each of them using your plant spray ability (the same button as it would be to Spin, normally). Note that the last one requires you to knock some boxes off the ledge in order to cross the small bridge and get to it.
Once you've done that, the Pagie reward is yours!
Glitterglaze Glacier Mollycool location, Dr Puzz, and Transformation
Dr Puzz location - From where Trowser is, go right to the far area with the towers looming above, and she'll be at the edge. Alternatively, exit Crystaline Caves from the larger, lower entrance and go straight ahead, and she's on the right.
Glitterglaze Glacier Mollycool location - Above Dr Puzz are a series of towers. At the tower furthest away from Dr Puzz is a pellet plant.
Eat it to load up, then then quickly head to the nearest high tower (you can do a glide from the tower to the bridge before it if you aim correctly) then spit a pellet at the rocks at the back of the tower to reveal the Mollycool.
Transformation - a Snow Plough. Use this to knock over the giant piles of snow dotted around the world to get snowman hats, which are requested by snowmen throughout the world. This is quite a convoluted affair, of which we have a dedicated snowman locations page for.
Need more help? Our Yooka-Laylee guide and walkthrough explains how the retro-styled platformer works and how to defeat each boss. If you're after collectables, here's where to find all Mollycool locations, Ghost Writer locations, Play Coin locations, Butterfly Booster locations, Power Extender locations and where to find the secret Pirate Treasure locations. Meanwhile, our complete list of quiz answers will help you outsmart Dr Quack.
Moodymaze Marsh Mollycool location, Dr Puzz, and Transformation
Dr Puzz location - As you stand and look towards Retrox's Arcade machine from across the final body of water before it, Dr Puzz and her DNRay are in the far back-right of the murky pond. You need to complete a task to earn a pagie before you can get across though, which turns the damaging marsh into swimmable water.
Talk to the nearby Trolley, pull the block behind the grate nearby onto the button in front of it using Lizard Lash, and then hop onto the buttons on the platforms above the water before the timer runs out to get the Pagie, which also opens up the path ahead by cleaning up the water.
Moodymaze Marsh Mollycool location - This is underwater in that same pond. In the centre of the underwater area there's a kind of podium, and you'll see the Mollycool behind the grating there. Use your Bubble ability to spin attack the top of the cage, and the lid will come off, floating up to become a platform on the water. That then lets you grab the Mollycool inside.
Transformation - a school of Piranha. This lets you swim underwater without worrying about running out of air. It also lets you clear away the little piles of bones found dotted around underwater by using the same button as it would be for Yooka's spin, and lets you pass through clusters of underwater thorns as well.
Capital Cashino Mollycool location, Dr Puzz, and Transformation
Capital Cashino Mollycool location - When you enter the level, go right then immediately left to find Dr Puzz.
To get the Mollycool, there is a slot machine opposite and to the right - spin the arm with your tongue and match three Yooka Laylee symbols (ground pound just before each one appears) and you'll receive it.
Transformation - Use it on the Dr Puzz's ray and you'll turn into a helicopter, allowing you to fly around the map, and comes in handy for collecting the level's Health Extender, yellow Ghost Writer and grabbing some extra Quills.
Galleon Galaxy Mollycool location, Dr Puzz, and Transformation
Galleon Galaxy Mollycool location - Get the Solar Shield move from Trowser straight ahead of where you begin, and head up the ramp and past the forcefields using it, and activate the lighthouse on this hill, giving you a Pagie as well as calling over Dr Puzz to the lighthouse's base, to the left of Trowser near the water.
To find the Mollycool, simply fly on top of the lighthouse, where it's sat right at the top.
Transformation - The ray will turn you into a boat with various elemental attacks to solve puzzles and safely explore the waters.
This transformation is pretty essential - it's required to get many Pagies and other collectibles, as well as reaching World 5 boss Planette.
Additional reporting by Matthew Reynolds.