Dango

Dango (ダンゴ) is a bug Badnik that from Sonic the Hedgehog CD. Green ones appear in Stardust Speedway, whereas orange-brown ones appear in Metallic Madness.

Description
It is not listed in any instruction manual, however it is referred to as "dango" in the game's source code. If Sonic approaches them, they roll into a ball and charge at him; in ball form, he can repel them. But if Sonic is fast enough, he can destroy them while they are not in ball form by rolling. When they are seen broken down due to age in the bad future or sometimes in the present, these Badniks' bodies are fractured and roll slower.

Trivia

 * "Dango" is short for "Dangomushi" (ダンゴムシ), the Japanese word for "Pill Bug".
 * The Dango appears to use the same concept as the Roller from Spring Yard Zone. The only real difference is that they are invincible when in its ball form, while the Roller is easily destroyed.
 * The green Dangos from Stardust Speedway have no known damaged form.