I don't know much about the Sydney mines, but from the context, I can infer that the tunnels were unsafe. Whether being that they were collapsing, or they were filled with poisonous gasses.
Answer:
they slither
and they wiggle
and they slither more
and then they wiggle more
Explanation:
Trees help purify our air. When the air is to contaminated trees take in all that contamination so we can breathe better.
