|This article is about a/an monster in Jikuu Senshi Spielban.|
Seaja (ウミジャ?): An octopus-based monster and Dr. Bio's final lifeform. Seaja was covered in tentacled limbs and was colored bluish grey. Seaja was unleashed into the ocean where it would spawn from its arms. Dr. Bio's plan was to infect all the earthlings with small aquatic parasites causing the infected person enter the ocean where they would turn into fish people. Spielban went scuba diving and confronted Seaja. He told Diana what was going on and she volunteered herself as bait to lure Seaja out of the water. Meanwhile, Spielban stumbled into Bio's hidden mountain lab and demolished it with his land vehicle. Diana, meanwhile, was engaged in battle with Seaja, who could spit out a sludge-like material from the large opening on its face and Diana was hit by it. Spielban managed to join in the battle and kill the monster. After Seaja was destroyed the victims of the parasites were freed of their manic need for the ocean.