Cornulitida is an extinct order of encrusting animals from class
Tentaculita, which were common around the globe in the
Ordovician to
Devonian oceans, and survived until the
Carboniferous.[1][2][3] Organisms that may be the oldest cornulitids have been found in
Cambrian sediments of Jordan.[4]
Cornulitids had shells, and were subject to predation by boring and other means from the Ordovician onwards. Many survived attacks by predators.[1] Several cornulitids were endobiotic symbionts in the
stromatoporoids and
tabulates.[5][6][7]
Their affinity is unknown; they have been placed in many phyla, and have been considered worms, corals, molluscs and more.[1] They appear to be closely related to other taxa of uncertain affinity, including the
microconchids,
trypanoporids and
tentaculitids.[1]