Leucothea

https://c1.staticflickr.com/5/4067/4264525351_7bf01344ee_b.jpg
"But comb jellies, Moroz and his colleagues found, lack those neuron-building genes altogether. Which means that comb jelly embryos must build their neurons from a different set of instructions—instructions no one yet understands."
https://www.google.com/amp/s/relay.nationalgeographic.com/proxy/distribution/public/amp/news/2014/05/140521-comb-jelly-ctenophores-oldest-animal-family-tree-science
https://montereybayaquarium.tumblr.com/post/171098069073/raising-the-beautiful-sea-goddess