diff --git a/phy_export.py b/phy_export.py
index af7e38d..7a68992 100644
--- a/phy_export.py
+++ b/phy_export.py
@@ -13,6 +13,8 @@ def write(filename):
     out = file(filename, "w")
     sce = bpy.data.scenes.active
     for ob in sce.objects:
+        if ob.name[0] == '_':
+            continue
         if ob.type == 'Mesh':
             if len(ob.data.faces) == 1:
                 # found a plane