Submitted by micro_haila t3_z4d27j in explainlikeimfive
Edit: Big appreciation for all the replies! But I think many replies are revolving around the flesh changing chemical composition. Please see my lines below about SEAWEED too - it can't be the same phenomenon.
It's not simply a salty flavour, but something else that makes it all taste seafoody. What are those components that all of these things (both plants and animals) share?
To put it another way, why does seaweed taste very similar to animal seafood?