Sitecore buckets are useful to store and manage millions of items with in Content tree, retrieving them and working with them in a speedy and efficient manner.
Items within the bucketed item are hidden and searched to view or edit using Sitecore search engine.
Even when the bucketable items are hidden in the item bucket you have option to view the items by selecting the Bucket checkbox in Content Editor, on the View tab, in the View Group
All items hidden in bucketed item-
However it is recommended to clear the Buckets checkbox when working with buckets. This will prevent the system from loading unnecessarily all items in the content tree. Search tab can be used to find and work with the hidden content items.