It continues to fuck me up that kelp is just Really Big Algae, which technically means that kelp is not a plant. Nope, they're protists, specifically Chromista. They're more closely related to diatoms than planty-plant seagrass. And if you're like "what's a diatom?" that is part of my point, but if you know what a diatom is, "what do you mean the organism famous for towering underwater forests is more related to the wacky miscroscopic glass bead organisms than actual plants?!" then YEAH ME TOO.
Basically I'm thinking about how often convergent evolution results in Thing looking like Something Else, producing obvious and easy categorization for the humans looking at them, but someone had the bright idea to arrange formal taxonomy based on shared ancestors, which is entirely sensible on its faceโ dog from wolf, wolf from vague toothy mammal, very sense-making!โ but doesn't have any way to cope with all those lifeforms convergently hopping in and out of niches for a billion years like a demented version of musical chairs. So THIS fish made dinosaurs and THIS fish made a fish which looks the same as the fish that made dinosaurs but ACTUALLY the last time they shared an ancestor was in the "yo, you wanna try this backbone shit?" days and thus we get to live in a world where the only way to reconcile cladistics with how the world LOOKS like it should work is to crack jokes.
