Post #4111878

Those aren’t quite as specified as horseshoe crabs though (which are a taxonomic family, just above genus and species respectively). Sponges and jellyfish are both much more varied and encompass more than one class. Similarly I can say that Reptiles beat horseshoe crabs since they’ve been around at least ~50 mya longer than the latter, but that wouldn’t really be a fair comparison because they encompass far more species than just horseshoe crabs. Regarding lasting a long time evolutionarily while staying relatively the same, horseshoe crabs are still uniquely notable. They aren’t called living fossils for nothing.