During Raid Mode, they tend to appear in optional areas. Upon defeat, they will reward the player with usually a Weapon Case or Custom Parts, which has a high probability of containing a rarer item.
They have extremely low health, but incredible defense - so much that it renders most weapon attacks to a minimal damage. Their only attack is jumping at the player, dealing minimal damage with their spikes. When damaged themselves, they try to get away by flopping around on the floor.
After defeating original Norman on the bonus stage "Ghost Ship", player(s) will encounter giant Aculeozzo of level 60 along with other Ghiozzo's.
In the 3DS version of the game, they are treated as Ghiozzo's contributing to their wanted mission counter when defeated.
In the port version of the game, Aculeozzo count as "Fish" type enemies affected by the "Poisonous Lure" custom parts.
The Aculeozzo's high defense means that killing one can deplete your ammo reserves. Shock grenades however, do significant damage. With a well placed throw, the blowfish can be killed with a single one. As they aren't particularly dangerous, using the knife to attack them is also a good option to conserve ammo, which reveals a surprising secret; Aculeozzo are weak against knife attacks.