"They can survive in an atmosphere that's
TWENTY PERCENT PURE OXYGEN. They actually need it to function!"
"If you breach their outer surface, an aqueous solution squirts out. On top of that, the weather on their homeworld regularly involves pure water falling from the sky. They live on the surface anyway."
"They progressed from tool use to apex species in only about 100000 generations. They went from writing to spaceflight in less than 500. They are about to create artificial intelligences based upon their own."
"They are covered and filled with some form of microscopic biological material that completely overwhelms any compatible surface in a matter of days. Attempts to eradicate it result in rapid adaptation."
"They have some form of mental superpower that allows them to defy logic and reason. All of their recent technology has resulted from generating seemingly random propositions and then gathering the evidence necessary to prove those false, rather than generating only propositions that conform to existing evidence."