Enterprise in an atmospheric layer of liquid phosphorus
Phosphorus is a non-metallic chemical element. One form of phosphorus emits a faint glow.
Liquid phosphorus comprised one of the atmospheric layers of a Class 7 gas giant discovered by Enterprise NX-01 in 2151. (ENT: "Broken Bow")
Crystals found on the USS Exeter in 2268 were comprised of 35% potassium, 18% carbon, 1.5% calcium and 1% phosphorus – all elements found in the Human body. It was later determined that the crystals were in fact the remains of the Exeter crew. (TOS: "The Omega Glory")
The alien retro-DNA that infected Geordi La Forge, Susanna Leijten and other away team members on Tarchannen III caused glowing splotches on the skin referred to as "phosphorus trails" in the script. (TNG: "Identity Crisis")