The Hallstatt Limestone is the world's richest Triassic ammonite unit, yielding specimens of more than 500 ammonite species.
Along with diversified cephalopod fauna — orthoceratids, nautiloids, ammonoids — we also see gastropods, bivalves, especially the late Triassic pteriid bivalve Halobia (the halobiids), brachiopods, crinoids and a few corals. For microfauna, we see conodonts, foraminifera, sponge spicules, radiolaria, floating crinoids and holothurian sclerites — polyp-like, soft-bodied invertebrate echinozoans often referred to as sea cucumbers because of their similarities in size, elongate shape, and tough skin over a soft interior.