# Fixing bad geometry on a complex mesh

I have been modeling a dragon, and I see all sorts of artifacts in the mesh. When I go into edit mode and select all by trait, blender says they are non manifold and interior faces. I have researched many different ways of fixing bad geometry such as merge by distance, Weld modifier, and trying to smooth or use other tools in sculpt mode.

Here is my .blend -->

• Did you try select non-manifold operation and see what's going on that mesh? Apr 28 '20 at 1:24
• If it says "non-manifold" it means you have inner faces that need to be deleted. Apr 28 '20 at 8:12
• I had selected non-manifold, but the highlighted areas appeared to be "outer" faces and I did not want to delete those important parts of the mesh. I believe the artifact was caused by using the decimate modifier as described in Xylvier's answer. Apr 29 '20 at 18:32