4.1.1 The System.ValueType type
All value types implicitly inherit from the class
System.ValueType, which, in turn, inherits from class
object. It is not possible for any type to derive from a value type, and value types are thus implicitly sealed (Section 10.1.1.2).
System.ValueType is not itself a value-type. Rather, it is a class-type from which all value-types are automatically derived.