Mountain jellyfish are large gelatinous creatures with multiple tendrils capable of producing poisonous thorns.
The creatures are land-based and roughly 160cm in height. Their bodies have two stars on either side of their "face" and they have two small eyes and a red mouth - their tentacles are darker in color. The creatures are sentient, understanding human speech and being capable of formulating plans, often attacking with their tentacles far from their sensitive bodies.
Only one has been seen in the series, and was the subject of the survival training for first year Military Academy students in 2196. Team Remix Heart defeated it, but Cypher Albar managed to make it fight again after forcing its rampage to begin with. 
- BlazBlue: Remix Heart, Chapter 21