Kabasira
From Sonic Retro
Kabasira (蚊柱) is a badnik in Sonic the Hedgehog CD's Stardust Speedway. It isn't listed in any instruction manual, however it is referred to as "kabasira" (the Japanese word for mosquito column or swarm) in the game's source code. It is a small badnik that shoots out a smoke trail when it travels (and it doesn't travel very far). Just hit it (it will be the non-flashing piece) to destroy it.