I'm a doctor, not a mechanic
Legacy:Primitive
From Unreal Wiki, The Unreal Engine Documentation Site
UPrimitive is the native-only parent class for all 3-dimensional shapes used in the UnrealEngine.
Known Subclasses
Primitive +- ConvexVolume → used for the shapes of AntiportalActors +- FluidSurfacePrimitive → used by FluidSurfaceInfo +- Mesh | +- LodMesh | +- SkeletalMesh | +- VertMesh +- MeshInstance | +- LodMeshInstance | +- SkeletalMeshInstance | +- VertMeshInstance +- Model → used for the shapes of Brushes and Volumes +- ProjectorPrimitive +- StaticMesh +- TerrainPrimitive → used by TerrainInfo