siburanlai's Identifications

On a stump of a chopped down tree.
It had just rained, however I believe this fungus was growing here some time ago already.

The stump itself is pretty hollow, with a colony of ants living inside and burrowing in.
Sadly couldn't document the ants as they were too small to get a photograph of.
Not too sure if this fungus benefits from the ants or vice versa.

As for the ID, there are multiple species from several groups that look similar, so I can't tell at first glance.
May update when I get back to my house.