Echinoderms have evolved diverse and disparate morphologies throughout the Phanerozoic. Among them, blastozoans, an extinct group of echinoderms that were an important component of Paleozoic marine ecosystems, are primarily subdivided into groups based on the morphology of respiratory structures. However, systematic and phylogenetic research from the past few decades have shown that respiratory structures in blastozoans are not group-defining and they have re-evolved throughout echinoderm evolution. This Element provides a review of the research involving blastozoan respiratory structures, along with research concerning the morphology, paleoecology, and ontogeny of each of the major groupings of blastozoans as it relates to their corresponding respiratory structures. Areas of future research in these groups are also highlighted.

Imaging and visualizing fossils in three dimensions with tomography is a powerful approach in paleontology. Here, the authors introduce select destructive and non-destructive tomographic techniques that are routinely applied to fossils and review how this work has improved our understanding of the anatomy, function, taphonomy, and phylogeny of fossil echinoderms. Building on this, this Element discusses how new imaging and computational methods have great promise for addressing long-standing paleobiological questions. Future efforts to improve the accessibility of the data underlying this work will be key for realizing the potential of this virtual world of paleontology.

The ability for people to connect, learn, and communicate about science has been enhanced through the Internet, specifically through social media platforms. Facebook and Twitter are well-studied, while Instagram is understudied. This Element provides insight into using Instagram as a science education platform by pioneering a set of calculated metrics, using a paleontology-focused account as a case study. Framed by the theory of affinity spaces, the authors conducted year-long analyses of 455 posts and 139 stories that were created as part of an informal science learning project. They found that team activity updates and posts outside of their other categories perform better than their defined categories. For Instagram stories, the data show that fewer slides per story hold viewers' attention longer, and stories using the poll tool garnered the most interaction. This Element provides a baseline to assess the success of Instagram content for science communicators and natural science institutions.