a moss snake

• 1014, 151, -30 (seen once) (2 of 4 spawns here)
• 39, 61, -52 (seen once) (2 of 6 spawns here)
• 63, 87, -52 (seen once) (2 of 4 spawns here)
• -89, 4330, -52 (seen once)
• -559, -1208, -53 (seen once)
• -127, -288, -53 (seen once)
• -121, 4976, -71 (seen once) (1 of 2 spawns here)
• 76, 2073, -52 (seen once)
• -222, 1474, -52 (seen once) (1 of 2 spawns here)
• -351, 3786, -54 (seen once)
• 70, 2322, 30 (seen once) (1 of 2 spawns here)
• -420, 2075, -52 (seen once)
• -325, -921, -51 (seen once) (1 of 2 spawns here)
• -591, 4495, -52 (seen once) (1 of 2 spawns here)
• -436, 3947, -44 (seen once)
• -250, 539, -53 (seen once)
• 209, -650, -52 (seen once)
• -545, 3985, -44 (seen once) (1 of 2 spawns here)
• 594, 312, -52 (seen once) (1 of 2 spawns here)
• -434, 458, -52 (seen once) (1 of 2 spawns here)
• -195, 215, -52 (seen once) (1 of 6 spawns here)
• 868, 274, -20 (seen once) (1 of 7 spawns here)
• -505, 192, -16 (seen once) (1 of 3 spawns here)
• 932, 141, -1 (seen once) (1 of 5 spawns here)
• 357, -145, -68 (seen once)
• -201, 619, -52 (seen once) (1 of 4 spawns here)
• -357, 1633, -43 (seen once) (1 of 2 spawns here)
• 195, 116, -58 (seen once) (1 of 8 spawns here)
• 375, 278, -54 (seen once)
• -455, -1597, -51 (seen once)

As /loc gives them: Y, X, Z, the most used first; nearby spawns share a spot, and one seen in a single visit may be where the mob had been pulled to.