Asteron

Asteron (テルスター) is a hovering starfish-type badnik created by Doctor Robotnik. Making first appearance in Sonic the Hedgehog 2, Asteron badniks are simply designed badniks, that are located usually on walls and are able to self-destruct and fire its five sharp parts to toward directions.

Sonic the Hedgehog 2
Asteron makes debut appearance in Sonic the Hedgehog 2, where it is one of three deadly badnik types featured at Metropolis Zone. These badniks hide at walls, floors and ceilings, where they cannot be harmed. When approached, however, it will move closer to the player, and then fire its star points, which are like spears, in five different directions. Its red eye helps it to detect the player when they are close enough.

In a certain part of Metropolis Zone, there is a giant tower which can be scaled by running up a screw on a nut, and there are about four to six Asterons along the way. Their threat is increased as their spear attack can cause the player to fall off the nut, often requiring the player to move a certain distance away from the screw to reset the nut at the bottom.

Sonic Pocket Adventure
Asteron badniks make next appearance in Sonic the Hedgehog Pocket Adventure, where they are featured at Gigantic Angel Zone. As Gigantic Angel has many identical gimmicks and elements from Metropolis Zone, it has also badniks models with same patterns as well. However Asteron badniks are seen hovering in the air and the player apparently is able to destroy these badniks before its self-destruction, thus freeing animal friend inside of it. Asteron badniks also are seen flashing red before its exploding.

Sonic the Hedgehog 4
Asteron then make reappearance in Sonic the Hedgehog 4, with slightly different design and being featured at Mad Gear Zone with same badniks. Despite that, these badniks retains the identical patterns from previous appearances, but once again the player is not able to destroy these badniks. Before its self-destruction, these badniks starts spinning around.

Physical Appearance
Asteron has simple, flat starfish-shaped appearance. Its core body is colored light-yellow and in the middle of the body is grey hole with red eye on the hole. All five sharp points have grey spears, that are pointing to the five directions. Asteron's appearance in Sonic the Hedgehog 4 is detailed, even through involving only slight changes.

Abilities
Asteron badniks can found hiding in walls, floors and ceilings, waiting its target to come closer of it and as these badniks are located on these places, they are mostly be harmed. When the victim approached closely, Asteron then moves closer to toward, and suddenly self-destruct itself and fires all five spears to five directions. When it's about to explode the player is able to know as the badnik's eye or the whole body itself starts flashing red for few seconds when it's moving forward.

Sonic the Comic
Asteron has made few appearances in Fleetway's Sonic the Comic, as being typically part of Robotnik's badnik army. The only appearance in the comic's original run has been in issue 79's story "Revolution", where Asteron was as one of the badniks unleashed on the civilians to remind them that Doctor Robotnik was in charge Brutus' troops are seen to feature one Asteron as well. All of these badniks have got destroyed by Sonic, Amy and Johnny Lightfoot. Before that, Asteron has also featured on one pin-up of issue 67.

Archie Comics
Several Asteron badniks made small appearance on one panel of Archie's Sonic the Hedgehog comic issue 229. They are guarding Metropolis Zone like other badniks during the Genesis story arc., as Sonic tries to get past of them as he tries to get to the core of the Eggman's base.

Trivia

 * By hacking Sonic the Hedgehog 2, it is apparently possible to destroy Asteron badniks simply by Spin Jumping on them and freeing animals inside them, if these badniks aren't set on to walls. Because the original game doesn't let the player to have change to destroy these badniks, animals inside of them can be possibly get perished after badnik's self-destruction.
 * Asteron and Crawl are the only Badniks in Sonic the Hedgehog 4, that are not featured in the game's website.