The ants are in the upper center of the photo and tiny, only about 2mm long. They have collected this flotsam and jetsome. At first I thought it was just a pile of dust in the corner and swept it away but in a few hours the'd collected a new pile. I really can't tell what any of it is. For scale the pile is 3cm wide.
This looks like a 'kitchen midden' - these may include discarded food scraps, ant corpses, and other detritus. Some species of small ants seek out and scavenge in the middens of larger species.
Ok great thanks very much.
