Animal phyla

thumb|Chrysaora fuscescens|Pacific sea nettles, Chrysaora fuscescens

Ctenophora (; : ctenophore ) is a phylum of marine invertebrates, commonly known as comb jellies, that inhabit sea waters worldwide. They are notable for the groups of cilia they use for swimming (commonly referred to as "combs"), and they are the largest animals to swim with the help of cilia.

Placozoa ( ; ) is a phylum of free-living (non-parasitic) marine invertebrates. They are blob-like animals composed of aggregations of cells. Moving in water by ciliary motion, eating food by engulfment, and reproducing by fission or budding, placozoans are described as "the simplest animals on Earth". Structural and molecular analyses have supported them as among the most basal animals, thus constituting a primitive metazoan phylum.

Trilobozoa, from Ancient Greek τρεῖς (treîs), meaning "three", λοβός (lobós), meaning "lobe", and ζῷον (zôion), meaning "animal", is a phylum of extinct, sessile animals that were originally classified into the Cnidaria. The basic body plan of trilobozoans is often a triradial or radial sphere-shaped form with lobes radiating from its centre. Fossils of trilobozoans are restricted to marine strata of the Late Ediacaran period.

The petalonamids (Petalonamae) or frondomorphs are an extinct group of archaic animals typical of the Ediacaran biota, dating from approximately 635 million years ago to 516 million years ago. They are benthic and immobile animals,