File Futurefragmentsv1017z Here

The ".z" at the end of the filename could indicate that the file is compressed. If so, "z" might refer to a specific compression algorithm or format, though commonly, ".zip" is used for compressed files. Without the full extension (like ".zip", ".zst", ".7z"), it's hard to determine the exact compression type.

xxd -l 32 futurefragmentsv1017z # or head -c 32 futurefragmentsv1017z | hexdump -C file futurefragmentsv1017z