Object exists in dba_objects but nowhere else

Hi,

We have an index named QUEST_SX_IDX***** which exists in dba_objects as a valid index object but doesn't exists in dba_indexes.

We started to check if the object was dropped and was actually in the recycle bin but we couldn't find it there either.

The problem is that this index refers a table in another tablespace which we are trying to export through transportable tablespaces and of course this index comes up in the integrity check.
However we cannot get rid of this index. Dba_objects thinks it's valid but we cannot find it in dba_indexes nor in the recycle bin and thus cannot drop it.