Confused with ByVal

[dee-u]

I have the ff. test code, could anyone point out what's happening here? Why is the passed Collection acting like it was passed ByRef?

Private Sub Command1_Click()
    Dim a               As Long
    Dim CollectionTest  As New Collection
    Dim StringTest      As String
    
    CollectionTest.Add "Data1"
    CollectionTest.Add "Data2"
    
    ' Loop before passing to test contents
    For a = 1 To CollectionTest.Count
        MsgBox CollectionTest(a)
    Next
    ' Pass it as ByVal
    TestByVal CollectionTest
    ' The newly added value can be seen here
    For a = 1 To CollectionTest.Count
        MsgBox CollectionTest(a)
    Next
    
    StringTest = " Not passed yet "
    MsgBox StringTest
    TestAnotherByVal StringTest
    MsgBox StringTest
End Sub
 
Private Sub TestByVal(ByVal c As Collection)
    c.Add "Data3 - Created by ByVal"
End Sub
 
Private Sub TestAnotherByVal(ByVal s As String)
    s = s & " was passed ByVal "
End Sub