Marrella splendens

Overview

Marrella splendens is a small arthropod with long, backward-projecting head spines and numerous body segments. Its repeated body structures and distinctive head ornaments stand out. It is also known from a fossil showing it in the process of molting.^[2]

Key facts

A moment of shedding the outer covering has been preserved as a fossil. A museum presents a molting specimen of Marrella described in 2004. Researchers can thus study not only the complete body but also a moment in its growth as it replaced its outer covering.^[2]

Time and place

This is a small Cambrian arthropod. The Cambrian spans roughly 540–490 million years ago. Museum accounts describe how numerous specimens have supported research into its body and molting.^[2][1]

The time range describes source context, not the complete duration of this species.

Size, form and skeleton

Two pairs of backward-projecting spines are present on the head, and 26 body segments are described. Numerous appendages follow the segments. The museum gives a reported maximum body length of approximately 25 mm, or 2.5 cm.^[2]

Habitat and reproduction

The molting specimen allows investigation of how it replaced its outer covering as it grew. It offers another view of life in a small body with head spines, segments, and appendages. Body form and life history are connected within the same fossil research.^[2]

Fossil discovery

Citing a 2006 study, the museum reports that more than 25,000 specimens had been collected. A specimen showing molting was also described in 2004. One exceptional moment among many fossils added to the story of its life.^[2]

References

1. International Commission on Stratigraphy (2024) — Geological time chart
2. ROM · Marrella splendens
3. National Museum of Natural Science — Shields and body of Naraoia
4. Royal Ontario Museum — Pikaia gracilens
5. Royal Ontario Museum — Marrella splendens

Research questions

What more can be learned when many specimens accumulate? Alongside typical body form, there is a greater chance of finding traces of brief events such as molting. Marrella illustrates the study of a small arthropod’s body and life through many fossils.^[2]

Observation

Follow the backward-projecting head spines along the repeated body segments. Picture the many appendages extending to the rear to reveal the complexity of this small body.^[2]