These immense beings drift effortlessly through the cosmos. Centuries are but hours to them. They spend their lives drifting through Nebula clouds, fully sustained by the energies in these clouds. As the clouds begin to settle into stars, they will search for a viable cluster and leave behind an "egg" before moving on in search of a new cloud. More akin to seeds, these planet sized eggs hold a copy of their essence and thrive in Red Giant systems. This seed will develop in the star's orbit and when the star collapses, the energy released stimulates the egg to finally hatch. This hatchling will continue growing in this energy field before it is ready to continue it's own journey.
(Some personal world lore I made with the support of my Patreon.)