 Naryllina mermanicum is a common species of cyboglinity in the Barents Sea. It has been observed to have a unique body segmentation pattern, which differs from other known species of this phylum. Its epistosoma is composed of two distinct regions, the postannular and trophosomal regions. The postannular region is derived from the endodermal tissue, while the trophosomal region is derived from the mesodermal tissue. Additionally, the species has a unique juvenile stage, which resembles the trochophores of anelida. The larval stage of the species is also unique, as it lacks peripodia, and instead resembles the late metatrakophore. The species is also found in deeper waters than previously thought, and its abundance varies greatly depending on the year. This article was authored by M. M. Kanafina, R. I. Gabitalina, N. N. Rimskaya Korsakova, and others.