Meteorite

Meteor is a gimmick that appeared in Sonic Adventure 2 and Sonic Generations''. ''They are orbs that are seen floating in the outside parts of the Space Colony ARK.

Description
Meteors are like in real life, orbs that fly through space at high speeds until it gets crashed into some planets. In gameplay, they have both hurting and useful side. In useful side, they can be used to open doors or refilling the Boost Gauge and many others. The other side is limited to the type of the Meteors which are mostly the Volcanic variants of them which are able to explodes when touched and hurt the player.

Sonic Adventure 2
In Sonic Adventure 2, they appeared in Meteor Herd, where Knuckles must used some of them which are standing on platforms to open indestructible doors by punching them at the doors. If Knuckles failed to direct it to crash a door by it, then it will return after just leaving the area that they were in, in the first place.

The other common type of them, is the Volcanic meteors that falls from space, float on the ground or connected to some asteroids. In all cases, touching them will hurt the player make him lose his rings. They also can destroy anything beside the player like the useful of their kinds. They appeared in Meteor herd, Mad Space and especially, in the battle between Sonic and Shadow.

Sonic Generations
In Sonic Generations, they appeared again during the battle with Sonic and Shadow. In this game, there are two kinds of them. One which is surrounded with blue aura which will fill Sonic's Boost Gauge, however it will hinder the player if he was not using the Sonic Boost

The other one appear when Sonic has collected the Energy Cores, which are colored purple. When crashed by one of them, the meteors will split into three shards which will fly trying to slow down Shadow by attacking him.