Planet of Origin: Paira, a planet on the same orbit as Earth but on the opposite side of the sun
The pairans are a pacific sentient non-humanoid species which developed an advanced civilisation capable of interplanetary space travel millenia ago and have been watching Earth for 4000 years. They look like 2 meters tall starfishes standing up on their 2 bottom legs and using their 2 middle legs for manipulation. A giant eye at the center of their body serves as their main sensory organ.
Pairan technology allows them to transmutate into another lifeform, a technique they used with humanity when they made contact with selected humans in 1956 to warn mankind of the danger of Planet R, a comet on collision course with our own as well as of the nulcear research, mainly the development of Urium 101, a substance much more powerful than regualr radioactive elements.The comet was finally destroyed thanks to the use of Urium 101 and the Pairans returned to their homeworld.
Source: Warning from Space or Mysterious Satellite (宇宙人東京に現わる Uchūjin Tokyo ni arawaru?, Spacemen Appear in Tokyo, Diaie, 1956. Director: Koji Shima, Writers: Gentaro Nakajima (novel), Hideo Oguni (screenplay). Jay Cipes and Edward Palmer (english dialogues)