Answer: Porifera
The animal phylum porifera constitute the sponges that is most like the protists that gave rise to animal kingdom. One evidence is that they have been defined as multi-celled immobile animals or metazoans that have water intake and outlet openings, which is connected by chambers lined with choanocytes or cells with whip-like flagella. Another evidence that supports this includes the lack of true tissue in sponges.