This starts as a small yellow flower on a weed.
The the petals drop and the centre sort of explodes out to make a prickly hemisphere.
The centre keeps getting bigger and rounder till you end with a round reddish purple burr, like you can see here: https://365project.org/gardencat/365/2022-06-26
I'm finding it fascinating how many people here are finding this news and interesting - I'm sure I studied creation of seeds in school, although that may have been A level Biology.