Noun
One of the peculiar minute chitinous hooks found in large numbers in the tori of tubicolous annelids belonging to the Uncinata.
Source: Webster's dictionaryAnother variety, duplicatus (closely spaced layers of the same type, one above the other), is sometimes found with cirrus of both the fibratus and uncinus species, and with altocumulus and stratocumulus of the species stratiformis and lenticularis. Source: Internet
The species uncinus is similar but has upturned hooks at the ends. Source: Internet