Minecraft has seen a lot of updates. Now, with the official announcement of the Wild update, Minecraft will at least get to version 1.19.
Updates often include new items, mobs and biomes as well as blocks and other useful features. Not all updates include every update. Sometimes items, blocks, or other things are left behind to make way for better and bigger options.
Recently, iron and gold were replaced by raw materials. Raw iron is more valuable than iron ore.
Many items were lost long ago, such as the Nether reactor core which is not in vanilla Minecraft. But what was it?
It was included in the 0.5 update of Minecraft Pocket Edition Alpha, and the 0.1 update for the New Nintendo 3DS Edition. Since then, the Nether reactor core was removed from all versions.
However, they could use Nether reactor cores to make Nether reactors. This would create a tower of Netherrack around the reactor. This tower was called the Nether Spire.
Six iron ingots and three gems were dropped by the cores of Nether reactors. This was the exact crafting recipe. These were obviously very expensive to make.
These items were made obsolete by the introduction of the Nether. Players in Minecraft no longer need to generate netherrack, as they can just go into the Nether.
Although Nether reactors are safer than other methods of getting those items, having a new dimension is better than a generator. These cores and reactors were no longer needed after the Nether was created.
They are not available in Creative, and they cannot be summoned. You can only access older versions of Minecraft or use a mod to get them.