Shishania is a chancelloriid and not a Cambrian mollusk.

The Cambrian evolutionary radiation is noted for its profusion of bizarre and unfamiliar body forms, many of which illuminate the early ancestry of major animal groups. The spine-covered fossil Shishania aculeata (Cambrian Stage 4, Yunnan, China) has been interpreted as intermediate between mollusks and their lophotrochozoan ancestors. Our new material challenges this interpretation. We propose taphonomic explanations for apparent molluscan features and instead identify prominent anatomical similarities to coeval chancelloriids from nearby strata. Our reinterpretation of Shishania as an early-diverging chancelloriid helps to consolidate a model for the early evolution of this enduringly problematic group of sponge-like metazoans. Editor's summary: The Cambrian explosion is known as a time when evolution "experimented" with a wide array of new body forms, the modern affinities of which are often incredibly difficult to identify. This difficulty not only arises because of their unusual morphologies, but also because of the age of the fossils, which can make identification of key traits challenging. One classic enigmatic example is Shishania, an elongated, bag-like creature covered in spines. Recent assessments have placed this genus as an early mollusk, but Yang et al. describe new specimens that challenge that interpretation, pushing this organism back toward the sponge-like chancelloriids. —Sacha Vignieri [ABSTRACT FROM AUTHOR]