When a stem cell divides, one daughter cell must maintain its stemness while the other specializes. Therein lies another truckload of requirements.
Think of all the frustrated longings, misunderstandings, jealousy, and more entailed by the fact that males and females constitute separate genders.
Ikaria wariootia is just another problematic Ediacaran fossil that could be anything from inorganic artifact to protozoan to cnidarian and yes, maybe a bilaterian worm.
Small putative trackways in Siberian rocks are giving evolutionists an opportunity to claim bilaterian animals preceded the Cambrian explosion.
Here are findings about Cambrian and Precambrian strata, and how evolutionists keep dodging the implications of rapid emergence of complex designs.