My T dug a deep burrow and covered the entrance – but I found mold?

[The Grym Reaper]

I wouldn't worry about mould too much unless it starts to spread uncontrollably, bits on the surface can be picked off, bits under the sub will most probably use up any nutrients in the subsrate and then die off.
I've had bits sprout up on one of the branches in my A. variegata enclosure (presumably because it isn't cork and I baked it before use), it hasn't caused any problems or spread to the substrate and it should just die off as it's pretty dry in there except for a water dish.

 

[Krystal Anne]

I wouldn't worry about mould too much unless it starts to spread uncontrollably, bits on the surface can be picked off, bits under the sub will most probably use up any nutrients in the subsrate and then die off.
I've had bits sprout up on one of the branches in my A. variegata enclosure (presumably because it isn't cork and I baked it before use), it hasn't caused any problems or spread to the substrate and it should just die off as it's pretty dry in there except for a water dish.

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Oh wow! Thanks so much for the info, that helps a lot.