It were small mole kind of mammals in their ground holes. Something like this <a href="https:&#x2F;&#x2F;en.m.wikipedia.org&#x2F;wiki&#x2F;Naked_mole-rat" rel="nofollow">https:&#x2F;&#x2F;en.m.wikipedia.org&#x2F;wiki&#x2F;Naked_mole-rat</a> - this one has very low metabolic rate for example.