Hello, I'm an expert in the field of cosmology and archaeology. When it comes to the question of the oldest thing in the world, we need to consider different contexts, as "oldest" can refer to various things depending on the scale we're looking at.

In the context of the universe, the oldest known objects are cosmic microwave background radiation (CMBR), which is the remnant heat from the Big Bang. This radiation is about 13.8 billion years old.

On Earth, when we talk about the oldest physical objects, we might consider items like stardust, which can be billions of years old and found within meteorites, or zircon crystals from Australia that are around 4.4 billion years old.

In terms of biological entities, some of the oldest known life forms are microfossils found in Australia, which are approximately 3.5 billion years old.

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This ancient zircon crystal is the oldest known material formed on Earth. Scientists have dated the crystal to about 4.4 billion years, making it the earliest confirmed piece of the planet's crust. The crystal was found in an arid region north of Perth, Australia, in a low range of hills called the Jack Hills, in 2001.read more >>