Carapace The carapace of
Protozoea, and other members of
Protozoeidae, is more elongated than in other
Thylacocephalans, however, the ratio between the carapace length and depth vary significantly from specimen to specimen. The most notable feature of the carapace are the two long spines on either end of the animal, with the rear one curving upward. Moreover, the carapace of
Protozoea would have been relatively light and flexible, which would have aided in faster, more pelagic movements.
Appendages Remains of the raptorial appendages are rare. In life,
Protozoea would have 3 pairs of delicate limbs that would have been articulated with muscle fibers at the base of them underneath the carapace. Notably, only the distal parts of the forelimbs would be visible from outside the carapace: a feature not seen in other
thylacocephalans. Behind the raptorial forelimbs, there is a series of small paddle-shaped limbs that would have aided the animal in swimming.
Internal Anatomy Preserved within the carapace of
Protozoea are various soft tissues, including the stomach, muscles, and 8 pairs of "
baguette-shaped" gills. Several muscles are preserved, including those that would have controlled the stomach movements as well as those of the trunk limb. ==Paleoenvironment==