The Meteorite is an obstacle/gimmick that first appeared in Sonic Drift 2. They are extraterrestrial rocks which the player can use to their advantage under special circumstances.
Meteors, like in real life, are rough boulders of extraterrestrial origin which are found floating around the Space Colony ARK. In gameplay, they can be found floating around in the playable environments where the player can interact with them. Under certain circumstances, the Meteorites can used by the player for special purposes, which differ between games, though in other cases they have been known to harm the player.
Sonic Drift 2
First appearing in Sonic Drift 2, Meteorites can be found flying above the race track of Milky Way. When racers are sent to the mid-air, there is a change that they can get smashed by a Meteorite, causing them to spin out and lose ground.
Sonic Adventure 2
In Sonic Adventure 2 and its later iteration, Sonic Adventure 2: Battle, the meteorites appear in Meteor Herd, Mad Space and Sonic and Shadow's finalbattle. In this game, the meteorites are either falling down from space, floating in midair or are connected to some asteroids, and will damage the player upon touch. In some cases, they can also destroy breakable objects.
In Meteor Herd, a special form of Meteorite appears, which is referred to as "Meteorech". These meteorites float on plaforms for Knuckles to sent them flying with a punch. By running and punching, the Meteorechs will fly farther. If sent flying into indestructible doors or containers, the Meteorechs will burst them open. After being sent flying, the Meteorechs will respawn when the player turns their back on them.
Shadow the Hedgehog
In Shadow the Hedgehog, Meteorites appear in the Stages onboard the Space Colony ARK where they float around in the space. In this game, when touched, the Meteorites will create a massive explosion and cause damage to the unprotected player. However, they can as well be intercepted in midair with attacks or guns to avoid the explosion they produce.
In Sonic Colors, the Meteorites can be found in Asteroid Coaster where they float around in asteroid belts in space. The player can use them in gameplay to cross otherwise impossible gaps by Homing Attacking across the string of Meteorites that appears.
During the boss battle against Frigate Skullian, the boss can open portals that will deposit multiple Meteorites at Sonic. Touching them will cause the player damage, so they are best avoided with ground movements or by Homing Attacking them.
The blue variant is encountered normally on the course where breaking them with the Sonic Boost will fill the Boost Gauge. However, they can halt the player if they simply run into them. In addition, they are absent entirely in Hard Mode of the battle. The purple variant is only encountered when Sonic has enough Energy Cores for a special attack. When boosting into these ones, the Meteorites will split into three shards and fly into Shadow, slowing him down.
In the Nintendo 3DS version, Meteorites appear in Tropical Resort Act 2 during the Grind Rail section before the Goal Ring. During the said section, several inflamed Meteorites will fall from the sky and ram at the rails. In order to avoid them, the player must stay away from the red circles that appear on the rails which mark where a Meteorite will land by using the Grind Step. If the player gets hit by one of the Meteorites, they will fall off of the rail and lose a life.
It can be assumed that the way the Purple Meteors split when touched by Sonic and tracking down Shadow, is linked to his empowered purple Boost, which may mean that Sonic gained a Telekinesis-like power by the Energy Cores.
↑Sonic Team (November 11, 2011). Sonic Generations. PC. Sega. Area/level: Shadow the Hedgehog. "Omochao: You got two Cores! Charge into a Meteorite to knock it at Shadow!"