Is this a hash file? Then what it is? How do I decipher it?

[SirDice]

I could be wrong, but I think MP3s start with ID3.

Yep.

dice@molly:/storage/media/Music/Godmachine/The God Machine - One Last Laugh In A Place Of Dying>hexdump -C God\ Machine,\ The\ -\ 01\ -\ The\ Tremolo\ Song.mp3|head
00000000  49 44 33 03 00 00 00 00  02 56 54 49 54 32 00 00  |ID3......VTIT2..|
00000010  00 11 00 00 00 54 68 65  20 54 72 65 6d 6f 6c 6f  |.....The Tremolo|
00000020  20 53 6f 6e 67 54 41 4c  42 00 00 00 26 00 00 00  | SongTALB...&...|
00000030  4f 6e 65 20 4c 61 73 74  20 4c 61 75 67 68 20 49  |One Last Laugh I|
00000040  6e 20 41 20 50 6c 61 63  65 20 4f 66 20 44 79 69  |n A Place Of Dyi|
00000050  6e 67 2e 2e 2e 54 50 45  31 00 00 00 11 00 00 00  |ng...TPE1.......|
00000060  47 6f 64 20 4d 61 63 68  69 6e 65 2c 20 54 68 65  |God Machine, The|
00000070  54 43 4f 4e 00 00 00 0c  00 00 00 48 65 61 76 79  |TCON.......Heavy|
00000080  20 4d 65 74 61 6c 54 59  45 52 00 00 00 05 00 00  | MetalTYER......|
00000090  00 31 39 39 34 54 52 43  4b 00 00 00 05 00 00 00  |.1994TRCK.......|

Zip files start with "PK", a rar file with "Rar!", a windows executable with "MZ" and a whole bunch more. File extensions are soo 1970's.