>>5047050
You mean how did they devolve!

An extinct class of Cambrian Ctenophores called scleroctenophora were hyper-advanced.
They were so hard that they didn't sag outisde of the water.
They had a hard internal "skeleton" composed of sclerotized tissue of unknown composition.
They had sharp spines.
They had many more comb rows for extra speed. From 16 to 80 instead of the modern 8.
Even their nervous systems seemed to have been far more advanced than that of modern Ctenophores.
Over time Ctenophores lost all these advanced features until they reached their modern forms.
Nobody knows why.

https://pmc.ncbi.nlm.nih.gov/articles/PMC4646772/#R16

https://www.sciencedirect.com/science/article/pii/S2589004221009111