a cauldron rat

• -1563, -1116, 166 (seen once)
• -75, -157, -12 (seen once)
• -563, -1227, -26 (seen once)
• 532, -1356, -277 (seen once) (1 of 2 spawns here)
• -693, -1410, -59 (seen once)
• -928, 236, -47 (seen once)
• -1000, -2015, 18 (seen once)
• -1016, -997, -189 (seen once)
• 710, -532, 24 (seen once)
• -607, -1568, -290 (seen once)
• -403, 291, 45 (seen once)
• -883, -108, -189 (seen once)
• 352, 116, 84 (seen once)
• 908, -293, 118 (seen once)
• 268, -734, -220 (seen once)
• -70, -810, 70 (seen once)
• -723, 333, 74 (seen once) (1 of 3 spawns here)
• 151, -195, -11 (seen once)
• -542, -1087, 8 (seen once)
• -526, -989, 37 (seen once)
• 38, -577, -10 (seen once)
• 691, -1166, -10 (seen once)
• -687, 77, -10 (seen once)
• -589, -1548, -305 (seen once)
• -1060, 57, -37 (seen once)
• -231, -958, 163 (seen once)
• -520, -970, 42 (seen once)
• -215, -1084, 75 (seen once)
• -181, -56, -113 (seen once)
• -1430, 574, 229 (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.