The central belief is that an invisible and undetectable Flying Spaghetti Monster created the universe. By contrast, nuclear submarines were virtually undetectable and invulnerable. Radiation deaths at Chernobyl were also statistically undetectable. The first was about the signature thresholds at which an aircraft is virtually undetectable. The system is also said to be vibration-free, extremely quiet and virtually undetectable. Within a few hours, xylazine decreases to undetectable levels. Normally, children tend to have almost undetectable levels of NGAL. It is almost undetectable in adult human liver. Jim's hyperacute senses allow him to perceive things undetectable by normal humans. The idea of being unseen and hence undetectable has fascinated mankind for generations. Percolating columns of laterite removed enough cadmium, chromium and lead to undetectable concentrations. Neutrinos thus developed a reputation as being undetectable. Sufficiently processed lecithin is often undetectable with standard testing practices. Surprisingly, the Solwind pieces turned out to appear so dark as to be almost undetectable. Centimetric radar greatly improved interception and was undetectable by Metox.