Ok, so i’ll be sculpting along all is going well then suddenly…Zbrush will draw a start tool on the canvas…which I now have to go and clear then start sculpting again, been happening often, always the star tool…what gives, this is annoying and I hope its just something I’m doing wrong and not a bug.
The star is the PolyMesh3D default shape. The PolyMesh3D is a special tool designed to hold OBJ-type data.
When you import a mesh, what’s actually happening is that ZBrush is selecting the PolyMesh3D tool and then importing the model over it. If you then pressed Tool>Undo (or Ctrl+Z while in Edit Mode), that import-over function would be undone and the Tool reverts to its base shape.
(In the old days of ZBrush, you actually had to select the PolyMesh3D before you could import a model. That has since been streamlined so that it all happens in the background as soon as you press the Import button. But the undo effect remains the same.)