The cauldron, which was three feet tall, didn't have any unique carvings. It was just a simple and unadorned item cauldron.
Every alchemy stone chamber in the Alchemy Temple had a similar cauldron. Even the Divine-grade alchemy stone chamber had one.
These were the basic item cauldrons that the Alchemy Temple provided. They were nothing more than beginner-grade spiritual items. However, it was more than sufficient for a mortal-grade alchemy stone chamber, as these chambers were meant for Foundation Establishment Plane cultivators to use.
If the Golden Core Sage were to perform his alchemy, he would've used his own cauldron. The same would go for Nascent Zhenjun.
That was why cauldrons above spiritual item level were needed in Earth-grade and Divine-grade alchemy stone chambers. And just like other cauldrons, item cauldrons were expensive as well.