Primordials

In general, the entire class of creatures imbued, empowered, composed of, or otherwise connected powerfully with Primordial Magic

They gather and collect in stages. As the magic that they are coalesces and collects, the energy gathers and pulls into itself, and as it condenses, it can collect more from greater distances, until the ambient energy is not enough to feed on and get any bigger.
In denser regions, they can quickly evolve from nothing to straight up Elementals if they get the right spark going, which can happen like lightning amongst the clouds of Primordial Magic.
Their smallest form is that of a Motes, and their greatest is a Primordial Titan, mockeries of which can be found today in the form of infused giants.