Noblecrumpet's Guide to Slimes, Jellies, and Oozes is an outstanding resource for building more from oozes. This third-party supplement expands on the SRD's lore and stat blocks. From reading through it for further explanations on what the deal with oozes was, I can personally attest to it being a golden tome of inspiration. This isn't just because Skelly Jelly is the best thing to be named ever. The lore is top tier, there are so many glorious new oozes, and they all are beautifully sketched. For this guide, I focused only on anything that expanded officially established pieces of lore. Then got distracted for hours by the monsters in it.