In Spanish, it's "ajolote".

In the Spanish of the 1490s and early 1500s, there was a "SH" sound, spelled with X, the same way there is today in other Iberian languages like Portuguese, Galician, Catalan, or Basque. They got to Mexico and wrote many indigenous words with "SH" sounds (like "Mexico" and "axolotl") with X. Shortly after this, the pronunciation shifted to the modern Spanish J sound (which in much of the Spanish speaking world is like the CH in loch, but in some countries is like an H sound).