[2021] What's something really obvious that you took a long time realise was even a thing?

For me, I've played for about 1750 hours or so, and it wasn't until just yesterday that I finally realised that infested "Ancients" are actually infested orokin. Which is why they have one really big arm and one smaller one. I always knew the infested were made up of the other factions with chargers being grineer and runners being crewmen etc. But I'd genuinely never thought about what the ancients were, I'd assumed them to be some form of grineer like a really deformed scorpion. But no. I felt kinda stupid cause it took 1750+ hours to recognise.