This is another türbe or monumental grave, it stands some 15 meters from the Hüdavent Türbesi. It is the Gündoğdu and dates back the 14th century. It was built by Hakkı Kevvap (but a booklet by the ministry of culture and tourism from 2017 indicates “who built it and for whom it was built is not known”).
The dome seems to be pyramidical from the outside but spherical from the inside. I took some pictures of the graves inside also.