Plectostoma everetti (E. A. Smith, 1893) of South-Sarawak Borneo.
The specimen in the photo has a shell length of 1.5mm.
Plectostoma everetti within the Plectostoma genus of air-breathing land snails in the family Diplommatinidae which is a family of small land snails, also known as staircase snails. These extremely small snails appear to be adapted primarily to Limestone Hills.