Endoskeleton three phyla and one subclass of animals, endoskeletons of various complexity are found: Chordata, Echinodermata, Porifera, and Coleoidea. An endoskeleton may function purely for support (as in the case of sponges), but often serves as an attachment site for muscle and a mechanism for transmitting muscular forces. A true endoskeleton is derived from mesodermal tissue. Such a skeleton is present in echinoderms and chordates. The poriferan 'skeleton' consists of microscopic calcareous or siliceous spicules or a spongin network. The Coleoidae do not have a true endoskeleton in the evolutionary sense; there, a mollusk exoskeleton evolved into several sorts of internal
Bacterial phyla warrant a new phylum. Most of these are thermophiles and often also chemolithoautotrophs, such as Aquificae, which oxidises hydrogen gas. Other non-thermophiles, such as Acidobacteria, a ubiquitous phylum with divergent physiologies, have been found, some of which are chemolithotrophs, such as "Nitrospira" (nitrile-oxidising) or "Leptospirillum" (Fe-oxidising)., some proposed phyla however do not appear in LPSN as they were insufficiently described or are awaiting approval or it is debated if they may belong to a pre-existing phylum. An example of this is the genus "Caldithrix", consisting of "C. palaeochoryensis" and "C. abyssi", which is considered Deferribacteres, however, it shares only 81%