I didn´t have any problem with converting - neither with controlpoint setting nor with standard quads. history seems to be deleted on this geometry too. my SE said: select -r nurbsSphere1 ; nurbsToPoly -mnd 1 -ch 1 -f 3 -pt 0 -pc 200 -chr 0.1 -ft 0.01 -mel 0.001 -d 0.1 -ut 1 -un 3 -vt 1 -vn 3 -uch 0 -ucr 0 -cht 0.2 -es 0 -ntr 0 -uss 1 "nurbsSphere1"; // Result: nurbsToPoly3 nurbsTessellate3 // PS I didn´t change anything from your scene. I saw you use 6.0 and I opened/saved it with 6.5 so it´s of no use for you mate, sorry.