My iPS cells are not growing well and are dying. Recently, I spotted a mold-like colony in the culture and I observed these mini "tree-like" structures (see attached image) and realized they are on the underside of the culture dish. I managed to wipe it away with ethanol. The media colour is clear and normal with no obvious smell. The culture tested negative for mycoplasma but im not entirely convinced. Do anyone know what these structures are? Some kind of fungus? or mycoplasma colonies?