Nephrite

"The Centipeetle Mother" was host of the centipeetle group that raided Steven's bedroom in "Gem Glow." It also appears in "Monster Buddies", where Steven tames the Centipeetle Mother in its smaller form (which it acquired after Steven popped it's bubble) and sacrifices itself to save Steven. Steven says "I will heal you someday," but it is unknown whether the Centipeetle Mother will return again. It was confirmed that the Centipeetle is a gem in "Ocean Gem".

Appearance
The Centipeetle Mother takes in the form of a giant centipede. It is composed of several dark green segments that contain one pair of similarly colored legs, each segment is covered on the upper surface with a hard crystal covering. It's head is composed primarily of a gigantic pair of mandibles that fuse together near the base, it also contains a green crystal protuberance on the base that forms a broken horn-like structure, and the final segment containing no legs but what appears to be secondary mandibles. Right before it's head, it has a light cream colored mane. It's gem is circular in shape and colored light green with a dark green contour lines surrounding the circumference of the gem connected to a circular shape, and it is located inside the base of it's mandibles. It's gem acts as it's iris in it's eye.

After being released from the bubble in "Monster Buddies" and regenerating, it sports a heavily reduced form than it's previous incarnation. From it's body being composed of multiple segments, is now reduced to two segments. It's mane, head, and secondary mandibles have now been reduced in size as well. Also losing the crystal on it's forehead. It's gem now comprises the entirety of it's whole eyeball instead of just the iris.

Abilities
The Centipeetle Mother has the ability to produce and command Centipeetles that aid it in battle. It can also produce an extremely corrosive substance that can easily erode several media ranging from wood to stone to ice. It can use this corrosive substance as a projectile to attack from afar or assault enemies with a constant torrent of the substance to easily breakdown their defenses. It is also able to climb vertical walls and sheer cliff faces.

Trivia
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 * The Centipeetle Mother returns in the episode "Monster Buddies"
 * When the Centipeetle Mother was reforming itself after it escaped from the bubble, it took a humanoid form before taking its latest form.
 * It was revealed in the episode "Ocean Gem" that the Centipeedle Mother, along with most of the monsters previously fought, used to be Gems. Unfortunately, the Gem became corrupted, turning it into the monster it is now.
 * It can still eat with its mouth, even though its eye is also in its mouth.
 * It sacrificed itself in order to save Steven.
 * Many fans speculated the Centipeetle Mother used to be a Gem called Malachite, but Ian Jones-Quartey confirmed that the corrupted Gem that it used to be is not Malachite.
 * It's name is a play on the words centipede and beetle.
 * The monster resembles a centipede as it contains multiple segments that only contain a single pair of legs each and it also resembles a beetle in the sense that it has a hard covering that protects it per segment.