What phylum invertebrates that do not have germ layers?

The phylum of invertebrates that do not have germ layers is called Porifera, commonly known as sponges. Sponges are simple multicellular organisms that lack true tissues and organs, and they do not possess the three primary germ layers (ectoderm, mesoderm, and endoderm) found in more complex animals. Instead, their bodies are made up of a porous structure that allows for water filtration and nutrient absorption.