Tubular structure about 4-5 cm high. Surrounding area for about 30 cm had abundant small soil balls placed, often on top of each other and rising perhaps 10mm above ground level.
Although we don't actually have a photo of an ant, these nests are very distinctive, usually comprising the combination of soil and plant matter we can see in the photo. The ants also tend to be pretty shy and will retreat if disturbed. I think the recent rain has allowed them to rebuild the entrances , which would mostly have been smashed during the dry weather by the wear and tear of animals grazing etc. Fresh nest entrances have recently appeared on our property too. Cheers, Jon