This .NET class wraps the AcGeEntity3d ObjectARX class. It's an abstract base class for all point set classes. Any class that is derived from this class represents a set of points in 3D space.

Autodesk.AutoCAD.Geometry.Entity3d
    Autodesk.AutoCAD.Geometry.BoundBlock3d
    Autodesk.AutoCAD.Geometry.Curve3d
    Autodesk.AutoCAD.Geometry.CurveCurveIntersector3d
    Autodesk.AutoCAD.Geometry.PointEntity3d
    Autodesk.AutoCAD.Geometry.Surface
    Autodesk.AutoCAD.Geometry.SurfaceSurfaceIntersector

Public abstract Class Entity3d
Inherits DisposableWrapper
Inherits ICloneable

public abstract class Entity3d : DisposableWrapper, ICloneable;