From Sonic Retro
|Game: Sonic Advance
|Affiliation: Eggman Empire
|Hits to defeat: 1
Senbon is a pufferfish-like robot found in Secret Base Zone. Their concept and behaviour resemble the Pointdexter's: they float around back and forth in the air, and pause to extend their spikes. Obviously, they can't be harmed when their spiky bodies are inflated, so the player must wait until they deflate before using any attack on it.
This Badnik does not appear when playing in Easy mode.