[{_id:1,/** object ID*/name:"Oxford University",clubs:[{name:"Soccer",members:[{name:"Alice",age:22},{name:"Bob",age:23}]},{name:"Gymnastics",members:[{name:"Charlie",age:20},{name:"Dorothy",age:19}]}]},{_id:2,/** object ID*/name:"Cambridge University",clubs:[{name:"Chess",members:[{name:"Ellen",age:30},{name:"Frank",age:35}]},{name:"Go",members:[{name:"Gilbert",age:25},{name:"Hikari",age:40}]}]}]

db.collection.find({"clubs.members.age":{"$gte":40}})