Derren
Its a gadget which shows which phase the moon is currently with dots
Let the background be grey in colour
For full moon it would look like white dots in circle
As the days pass by the dots turn into black showing the shape /phase of the moon
Finnally for a new moon the dots will be black indicating it
If u want a diagrammatic representation pls do reply, will do n send em
Happy to help✌️✌️