<Tr> <Th> Created by </Th> <Td> J.R.R. Tolkien </Td> </Tr> <Tr> <Th> Genre </Th> <Td> Fantasy </Td> </Tr> <Tr> <Th_colspan="2"> In - story information </Th> </Tr> <Tr> <Th> Type </Th> <Td> Crystal ball </Td> </Tr>

What is the black ball in lord of the rings