Sandworms are likely another variant of Caterkillers due to their similar designs. The only significant differences between them are their color scheme. Originally, Sandworms were blue, orange and silver.
From Sonic Colors to Sonic Generations, they received an updated, more detailed design with cyan eyes and the spikes on their body segments having been replaced with metallic hatches. In Sonic Lost World, the Sandworms returned to their original design, but with cyan eyes. In Sonic Forces, the Sandworms received a more militaristic design. This time around, they were little more than segmented white cables with red and black circuitry inside them. Also, instead of heads, they had two laser guns and a white cap for a hat.
The size of Sandworms varies between games. Originally, they were about the same size as the original Caterkillers. In Sonic Lost World however, they are about five times larger than Sonic. The amount of their body segments has also varied; in Sonic & Knuckles, they had six body segments, in Sonic Colors and Sonic Generations they had five, and in Sonic Lost World they had only four.
Sonic & Knuckles
Sandworms first appeared in Sonic & Knuckles. They are only found in Sandopolis Zone where they sneak below the surfaces of quicksand. The displaced sand can be seen above them, creating a sort of ripple effect that shows roughly where they are. After a few seconds, they will stop and jump out in an arcing trajectory to another point in the sand. The player should be particularly vary about falling off platforms over quicksand pools since there is usually a pair of Sandworms hiding in them.
The Sandworms are best fought whilst they are in the air, but it is difficult to do so, especially when two of them jump out at the same time. The player can defeat a Sandworm by hitting its head with a Spin Jump as the rest of it is covered in spikes that will harm the player if touched.
In the Wii version of Sonic Colors, Sandworms are only found in Asteroid Coaster and in certain Acts in Game Land. In this game, Sandworms hide within small hatches. When the player gets close however, they will pop out and start firing relentless energy projectiles at the player. In most cases, they are best defeated with a Homing Attack.
In the console/PC version of Sonic Generations, Sandworms appear in Planet Wisp. In this game, their attack patters are the same as in Sonic Colors: they hide beneath hatches, but will pop out and shoot energy projectiles at the player when they get close. Also, in the game's hidden Statue Room, the player can unlock a statue of the Sandworm.
In the Wii U version, Sandworms are only found in Sky RoadZone 1 where they simply crawl forward. When fighting one, the player should hit its head using a Focused Homing Attack. Attacking any other body segment will not award the player with points and cause the Sandworm to dismember its body without releasing the Animal inside of it.
In the Nintendo 3DS version, Sandworms appear in Windy Hill Zone Tutorial Act, 1 and 2. Here, they pop out of hatches and are sometimes containing Springs or other objects within their body segments. While they can be avoided, it is occasionally mandatory to defeat them to progress through the Zone. In such cases, the player must attack their head with the Homing Attack multiple times. When a Sandworm's antennae sparkles, it will smash its head at the player, creating a short-ranged shockwave. However, this will leave it dizzy and open to the player's attacks.
In Sonic Forces, the Sandworms sport a modernized, militaristic redesign. The player only encounters them in Capital City.
In this game, the Sandworms possess the same attack patters they had in Sonic Colors and Sonic Generations: they hide beneath hatches, but will pop out and shoot energy projectiles at the player when they get close. In addition, there is a rare variant of the Sandworm in this game that works like a flamethrower.
Powers and abilities
The Sandworms are efficient burrowers capable of digging through the ground and moving through quicksand as it is water, and possess a harmful bite. Later generations of Sandworms were equipped with laser cannons that can shoot energy projectiles and could detach their spiked body segments from each other with ease. The giant versions of them also possess impressive strength.
In the Sonic the Comic series published by Fleetway Editions, the Sandworms are a part of Robotnik's Badnik army. Depending on the artist, the Sandworms' appearance would be different for each issue. During the comic's run, they only appeared in two issues.
Jazwares made several figures of characters from the Sonic franchise due to the announcement of Sonic Generations. There was a Modern Tails figure packaged along with a blue/gray Sandworm figure.
In Sonic 3D Blast, there is an caterpillar-type Badnik that appears in the Green Grove Zone and attacks like Sandworm. However, these Badniks are purple. Due to its coloring, it is possible that it may be a Caterkiller. Incidentally, they may be considered the same Badnik in Japan.
The Sandworm in Nintendo 3DS version of Sonic Lost World acts in a very similar way to the version of the Pokey enemy from the Super Mario Galaxy series, sharing attack patterns, defeat methods, and purpose of blocking paths.
Sandworms in Nintendo 3DS version of Sonic Lost World closely resembles the second boss of Sonic Chaos called Bead Worm Boss due its large size and both being based on caterpillars.