The Cambrian explosion took place about 545 million ago, and during 5-10 million years of that period, huge numbers of multi-celled complex organisms appeared. Most of these animal forms proliferated to the organisms of today, which are the entire extant phylum.

Fossils Lacking a Phylum
Hyolithes cecrops
Cone-shaped animals thought to belong to the Phylum Mollusca

Fossils Lacking a Phylum
Tentaculites richmondensis
Phylum Problematica - meaning no one knows for sure