The Worm is a secret level that can be reached from the Jungle or the Ice Caves via the tongue on the wall. The level is very narrow and very tall, three times the length of a normal level. It is the only place where the powerful Crysknife can be found.
Entering the Worm
While in the Jungle (2-1 only) or Ice Caves (3-1 only), you will see a pink sticky blob on the wall. This is the Worm's tongue. If you stick a Damsel to it — whether it is alive or not — the Worm will come out a few seconds later and will swallow it. As long as you hold the Damsel, the Worm will NOT appear. If you are stuck to the tongue as the Damsel is being swallowed, you will go in with it and enter the Worm. The easiest way to do this is to jump onto the tongue while holding the Damsel, release them, and then wait in place.
Note that you must stick the Damsel to the middle or top of the tongue if you want it to get swallowed and give you the +1 health bonus. If you stick it to the bottom of the tongue, it will fall off when the Worm comes. You will still be able to enter the level, but you will not get the health bonus.
Once the player has been swallowed, it's still possible to use the Action button to whip or use other items. This will look like a floating whip or shotgun bullets coming out of the wall.
Beware— Exiting the Worm will bring you to the last level of your current area (2-4 or 3-4). So if you enter the Worm from the Jungle, you will miss the Black Market, and if you enter the Worm from the Ice Caves, you will miss the Moai Head Statue. The Moai will, however, be present on 3-4 (#2) after beating the Mothership, which will allow you to still get the Hedjet after visiting the Worm and the Mothership.
Getting the Crysknife
Once inside the Worm, look for the large pool of acid about halfway down. You will see an odd-looking knife at the bottom of it. This is the Crysknife, a unique item found nowhere else in the game. Simply throw a bomb into the bottom of the pool to drain it, and then hop inside and grab the knife. (If you enter the pool without draining it, the acid will damage you. It is possible to jump inside, grab the knife, and jump back out if you have no bombs and enough health.)
Unlike every other weapon in the game, the Crysknife does not take up your held item slot; it actually replaces your whip. (This means that you can hold an item while also having the Crysknife equipped.) It one-hit kills every enemy in the game that can be damaged by hitting it. Also, it is one of the few weapons that can be used to kill Bacterium.
Special FeaturesThe Worm has many unique enemies. Green egg sacs (Worm Eggs) explode and release three to four Worm Babies. These are quite a threat considering these egg sacs are found frequently in the level and are often close together. If you jump on or whip an egg before it opens, it and its contents will be destroyed. (This releases a lot of blood, which is useful if you have a Kapala.)
You will also encounter a great number of Bacteria, which are invulnerable to most attacks. This makes them very difficult to get past during the first half of the Worm, where you must typically rely on avoiding them with timed jumps and backtracking. However, in the second half of the Worm you will hopefully have the Crysknife with you, which can kill them in a single hit. Note that if one does come into contact you, it will damage you but also kill itself in the process.
Every once in a while you will see a patch of square blocks that disappear when hit, then reappear a few seconds later. Be careful; if you are standing where one used to be, it will (in most cases) insta-kill you when it comes back. These are called "regenerating" blocks. If the regenerating blocks are destroyed by a UFO's beam, they will not regenerate.
In addition to the native enemies found in the Worm, you will also find other monsters the worm has swallowed from the area you entered from. When entering the Worm from a Jungle level, you will find Jungle enemies such as Frogs and Snails. When entering from the Ice Caves, you will instead see Yetis and UFOs.
- The Meat Boy Spelunker can by unlocked in the Worm by breaking him out of a green fleshy sac found near the bottom of the level.
- Be careful though, as unlike with the whip, one hit from the Crysknife will kill Meat Boy, but he will remain unlocked.
- The Ghost does not normally appear in the Worm, even after you spend 2:30 on the level.
- The Shopkeeper will only appear if the player is wanted by the Shopkeepers before entering the Worm.
- The Worm's tongue will not appear on 2-1 if the Level Feeling is "Restless Dead."
- It's possible to go on the right side of the Worm by using the teleporter; no blocks spawn there, but enemies can spawn at the floor at the bottom. This can be especially useful during speedruns, as long as the player has a way to prevent fall damage, uses a rope before falling, or stomps on an enemy before hitting the floor.
- If a Hired Hand is swallowed by the Worm, the player will be taken into it too.