Cricocosmia Chengjiang Nematomorph with Preserved Proboscis

Description: This Nematomorph worm is known as Cricocosmia. The species is known from numerous specimens, many of which have preserved details such as this fine example. The intestine is often preserved as a dark film as seen here, indicative of its deposit-feeding lifestyle. What is not typically seen preserved are the cone-shaped sclerites seen in paired longitudinal rows. Even more unusual is that fact that the everted proboscis has been presereved as well. The diversity of soft-tissue fossils is astonishing: algae, medusiforms, sponges, priapulids, annelid-like worms, echinoderms, arthropods (including trilobites), hemichordates, chordates, and the first agnathan fish make up just a small fraction of the total. Numerous problematic forms are known as well, some of which may have represented failed attempts at diversity that did not persist to the present day.

This group of worms is commonly known as the horsehair worms, and is represented by some 300 extant species. This one was originally thought to be a priapulid worm, a view still held by some researchers. It is only known from the Lower Cambrian of Yunnan Province.