What is up with the seahorse? It looks like nature hit the random button during critter creation. Where did it evolve from? what other sea critters is it related to?

I was speaking with my son while walking our dog the other day and we agreed that most critters seem to be a variation on other critters, be it a long neck deer or a chompy water rat. When asked about seahorse however neither of us could come up with an answer. So what is up with the seahorse how did it come be? What other animals can we see that it’s genetically close to? via /r/askscience https://ift.tt/2PTB0yB