Simplify the following text for a Grade 9 native English-speaking person.
Original: These rings have a clumpy structure , the cause of which is not currently understood but which may be due to the gravitational interaction with small moons in orbit near them .
Simplified: Neptune 's planetary rings have a weird `` clumpy '' arrangement . Although the cause is currently unknown but some scientists think that it may be because of the gravitational contact with small moons that orbit near them .