Grandfathered, No longer available
The Locationless Cache, also called the Reverse Cache, was a type of cache.
"Locationless caches could be considered the opposite of a traditional cache. Instead of finding a hidden container, you are given a task to locate a specific object and log its coordinates. A scavenger hunt of sorts, it involves collecting waypoints of various objects around the world.
Locationless caches involved the cache owner providing a description of a desired object and a desired task. Geocachers then had to locate an object matching that description in their travels. They could claim a find by meeting the requirements. Once the requirements were met at that location, nobody else could use that location to meet the requirements and claim a find.
As Groundspeak changed it's viewpoint on what defines a geocache, locationless caches were one of the first to be eliminated. It remains the only cache type that is no longer findable, as all locationless caches have been archived.
Exceptions to this are the newly published Signal the Frog in 2020 and Lets Improve the Outdoors A CITO based locationless cache published in Jan 2021 - both of these created and put out by Geocaching HQ
Similar types - virtual caches and webcam caches, like the Locationless cache were no longer creatable when this decision was made, but many still exist as they were not forceably archived if they had already been created. However HQ awarded 8000 virtual caches to cachers around the world - these were put out in two blocks of 4000 (2017/2018 and 2019/2020) - however there are still around 2000 of these yet to be published