444-year-old fossil belonging to the spider family with gut and brains intact has been found

In a shocking revelation, a 444 million-year-old arthropod fossil has finally been identified by palaeontologists. Discovered 25 years ago by Sarah Gabbott, the specimen had been preserved inside out with its muscles, tendons and guts exquisitely preserved and its limbs, carapace and head already dissolved.
During the first of the five mass extinctions in the planet's history, the Late Ordovician mass extinction wiped out nearly 85% of all life. It was during this period that the discovered arthropod met its end and became fossilized in Soom Shale- a band of silts and clays located 250 metres north of Cape Town, South Africa.
Over the years, intense glaciation layered waste on the planet, but this fossil surprisingly remained intact. It was 444 million years later that palaeontologists unearthed the fossil only to be unable to classify it with any of the existing fossils.

It was later when Sarah Gabbott published a on the fossil in the journal Paleontology, that the surprising discovery was made that the fossil was preserved inside out. Gabbott named the fossil Keurbos susanae with the nickname Sue after her own mother, who had always supported her love for palaeontology.
“‘Sue’ is an inside-out, legless, headless wonder. Remarkably her insides are a mineralised time-capsule: muscles, sinews, tendons and even guts all preserved in unimaginable detail. And yet her durable carapace, legs and head are missing—lost to decay over 440 million years ago” said Gabbott, the lead study author in a press statement.
While the place where the fossil was found included an anoxic environment which is required for fossilisation to occur, Gabbott thinks that the hydrogen sulphide dissolved in the water may have been the cause for the dissolved parts of the fossil. The mineral that preserved the fossil's insides is believed to be calcium phosphate. In a statement to IFLScience Gabbott revealed that she's still trying to work out the exact details of the preservation process.
Additionally, it is unknown where the discovered fossil lies in the arthropod family tree, even 25 years after Gabbott first discovered it. “This has been an ultramarathon of a research effort. In a large part because this fossil is just so beautifully preserved there’s so much anatomy there that needs interpreting. Layer upon layer of exquisite detail and complexity" added Gabbott in a statement.
Arthropods, which include invertebrates such as insects, arachnids and crustaceans, make up roughly 85% of the animal life on the planet and one of the most extensive and well-preserved fossil records.