There are different types of fossils, some of which apply to soft tissue:

• Impression: A shallow imprint of a fossil organism that does not retain any organic material.

• Compression: A fossil that has been crushed or flattened but retains some organic material, although it has been chemically altered.

• Carbonization: A process that occurs during fossilization in which complex organic molecules are converted into a more stable carbon compound that generally has a dark brown color.

This appears to be an impression fossil.

Happened all the time. It just depends on the environment. Check out basically anything on the "Tully monster" if you want to know more.

Tully monsters are actually even older than OPs fossil and we have no idea where they came from or where they went, from an evolutionary perspective.