Re: 'seeded' from the same extrasolar source
cephalopods (octopii and squid) are relatively easy to explain as early divergers from our wormlike ancestors. It's more obvious in the giant squid dissection video on youtube.
Like worms, octopii and squid brains surround the mouth and even our fishy ancestors had multiple hearts (one per gill) that evolved from worms' multiple parallel pumps. That only dropped down to one heart somewhere before amphibians as the simple inline pump became more complicated (if you look along the family lines you can see the "knotting" effect that produced 2, then 3 and then 4 chambered hearts.)
As for the blood, there's only a one atom difference at a critical location between chlorophyll, haemocyanin and haemoglobin molecules. (magnesium vs copper vs iron respectively). Nature seldom starts over when it can adapt existing items - which explains why things end up as Heath-Robinson messes a lot of the time.