From: Star Trek: The Next Generation
Caption: A Marijinian posing as Geordi's mother.
Telepathic subspace creatures who appear to humans as fire and live in lower depths of gas giant Marijne VII.
This sentient species is indigenous to subspace, yet appears like tiny chemical flames floating through space. Due to an accident in 2370, several of these beings became trapped in a ship and needed to communicate with humans. The Mariijne beings communicate by directly accessing thoughts which proved deadly to humans, so in order to communicate, the beings instead assumed the image of a familiar humanoid in an effort to find their way back to the safety of their home in low orbit around the planet.
A group, accidentally trapped about the Raman, tried to communicate with its crew of seven when it ascended from their eco-level and they died from the contact. One took the form of Geordi's late mother to talk to him when interfaced with a remote probe, with the contact not fatal due to his remoteness until close proximity.