Bubbles are loosely based on real-life pufferfish. Bubbles' blue body are smooth and spherical. Up front they have a nozzle-shaped head with two big black eyes on each side and a yellow neckline. Their rears also have a hole where a few wires go. On them, the Bubbles have a total of seventeen white spikes.
Since Sonic the Hedgehog 4: Episode I, Bubbles have become more detailed in appearance and their spike holes have turned purple and less visible. In return, they only have thirteen spikes on them. Their neck holes are also slightly larger, and under their bodies is a small rocket which keeps them floating. Their rearholes are also changed to seal air on each side of their body.
Sonic the Hedgehog 3 & Knuckles
Bubbles are first seen in the Marble Garden Zone in Sonic the Hedgehog 3, and its lock-on version Sonic the Hedgehog 3 & Knuckles. Like Spikers, the Bubbles are very deceiving with their innocent appearance. On their own, Bubbles hover around alone. When the player is closing in on a Bubbles though, it starts hovering toward the player and starts protruding and retracting spikes from its body. The Bubbles are best destroyed by Spin Jumping into them when their spikes are retracted. Alternatively, their thorny defense can be penetrated with Sonic the Hedgehog's Insta-Shield. However, the player must time their jump and Insta-Shield execution correctly, or the Bubbles' spikes will protrude to inflict easy damage on Sonic.
Sonic the Hedgehog (Didj)
In Sonic the Hedgehog (Didj), the Bubbles are enemies found in the Curricular Gadget#Letter CannonCurricular Gadget. In this game, they hover in midair from left to right, carrying black TV Monitors with one or two letters behind them. In gameplay, the player needs to aim the cannon they are in so that Sonic can hit and destroy the Bubbles with the right TV Monitor. If they destroy the right Bubbles, they will be rewarded with some Gold Rings. On the other hand, if the wrong Bubbles is destroyed, then the playable character will fall down using their "hurt" animation and return to the cannon. Should this instance occur three times in total, a voice will tell the player which Bubbles was carrying the right TV Monitor, before Sonic is taken back to the normal Act without being given any rewards.
Sonic the Hedgehog 4
In both episodes of Sonic the Hedgehog 4, the Bubbles returned as common enemies. In these games, they appear in two colors. The traditional blue Bubbles with spikes are present; however, due to Eggman's budget cuts, these Bubbles do not have spikes. Red Bubbles make their debut in these games and are slightly more dangerous as they can protrude spikes.
Diagonal chains of Bubbles are found in nearly every level. Many of these chains appear over bottomless pits, forcing the player to use the Homing Attack to skip across them. Unlike in Sonic the Hedgehog 3, Bubbles in Sonic the Hedgehog 4 will not chase after Sonic and will instead remain stationary.
The red variation of the Bubbles appear in Jungle Zone in the 2012 remake of Sonic Jump. Like in Sonic the Hedgehog 4, these Bubbles float in one place and protrude spikes quickly. However, the player can destroy them with the Spin Jump at the right time.
Powers and abilities
Bubbles can hover in the air with small rockets, despite that they did not need that in their first appearance. Bubbles have all their spikes hidden inside their bodies. While Bubbles can be harmless at first, they will reveal they spikes quickly and without any warning which can cause unexpected damage to the player.
Performing a Homing Attack right as Sonic is below a Bubbles will cause him to stay in his uncurled form, allowing the player to quickly bounce through the rest of the chain of Bubbles. This avoids the brief moment between Homing Attacks.
Bubbles' Japanese name "Harisenbo" is Japanese for "porcupinefish".