A Cactiball's name is an adequate description itself; the only other notable aspects of the monsters' appearance are limbs, small compared to the rest of its body, a devious face and a flower at the top of their head/body.
Cactiballs are fairly energetic given how they dance about in their idle animation. For their actual dances they will curl in their arms and legs and roll about. When attacking, a Cactiball will extend and enlarge its spikes and may perform a jumping attack that has a chance of landing a devastating blow. They aren't exactly dangerous monsters, however, as they are encountered early on in most of the games they appear in and will only pose a threat to a low-leveled player, though this can apply just as well to other monsters in the area.
When they get in a huff, watch out for their puff! You could get yourself caught in a real spinefield.
Cactiballs are Platiosi and thus members of the Plob in this spin-off game. They often wander about, occasionally stopping to shake some maracas, and will turn themselves into an unapproachable ball of spikes if Rocket gets too close. They are first encountered in Tootinshleiman's Tomb and later in Flucifer's Necropolis where they hide under the sand with only the tops of their heads exposed but will jump out and immediately extend their spikes if approached. Like other normal enemies, it is possible to have a Cactiball as part of the tank crew after sending at least 30 back to town and speaking to the Cactiball in the Museum.