Pearlweed (Micranthemum)

Pearlweed under its original genus name, Micranthemum micranthemoides, before it got shuffled into Hemianthus and back by taxonomists who apparently couldn't make up their minds. Same tiny round leaves, same fast branching habit that turns one stem into a dense green thicket within weeks under solid light and CO2. It's a workhorse foreground or midground filler, equally happy left bushy in the background or scissor-trained into a low carpet with regular maintenance. Nodes stay tight and compact when dosing is dialed in, but stretch out leggy the moment light or nutrients fall short, so consistency matters more than intensity here.