Nitrium Metal Parasites
History:
Spaceborne microscopic life-forms that ingest nitrium, converting it to a simple molecular gel.
These life-forms normally live in nitrium-rich asteroids, such as those found in the Pelloris Field near planet Tessen III. The
Enterprise-D was accidentally infested with nitrium metal parasites on stardate 45733, while destroying an asteroid that was on a
collision course for Tessen III. Because nitrium is used extensively in starship construction, the parasites caused substantial
damage to the Enterprise-D, nearly resulting in a warp-core breach.
TNG "Cost of Living" ; Star Trek Encyclopedia II
.