Orbinaut

Orbinaut is a metal ball ringed by four spiked balls that it throws at its prey. This is its only method of attack, and also its greatest weakness, as once all four spiked balls have been thrown, Orbinaut is completely defenceless. It's based on a sea urchin. It also appeared in the comics.

Unidus
Unidus (ウニダス) is a blue variety of Orbinaut that becomes red when a enemy is spotted and sends the four spiked balls around it forward to attack. It appears in the Labyrinth Zone from Sonic the Hedgehog.

Uni-Uni
Uni-Uni (ウニウニ) is a green variety of Orbinaut that keeps the four spiked balls around it for defense. It appears in the Star Light Zone from Sonic the Hedgehog.

Gola
Gola (ゴーラ) is a red variety of Orbinaut that has four fireballs (one in Sonic Blast) around it instead of spiked balls. It appears in the Hill Top Zone from Sonic the Hedgehog 2 and Red Volcano Zone from Sonic Blast. He made a return in Red mountain from Sonic Adventure and also appeared in Sonic Advance 2.

Star Pointer
Star Pointer appears in IceCap from Sonic the Hedgehog 3 and has four spiked ice balls around it. It sends the spiked balls forward to attack.

Orbinaut
Orbinaut is a metallic gray variety and appears in the Launch Base from Sonic the Hedgehog 3. It keeps the four spiked balls around it for defense, and only move when the player also move.

Spiky Spinner
Spiky Spinner is a variety from Sonic Adventure.