I confess, I hadn't really thought what coalescence" meant when I put it into my sample generator. So I was stumped for a while when it popped up. Hmm... drops bumping into others to make bigger drops?
A bit tricky to realise in embroidery, so for a quick but different sample I used my Japanese screw punch on coloured paper. I went crazy punching different sized holes in purple origami paper, then mounted it on contrasting purple paper.