If an object depends on another object that does not exist, then Oracle sometimes needs to represent that non-existent object in OBJ$ for dependency management reasons. Here is an example ...

        SQL> create table t as select * from dual;

        Table created.

        SQL> create view v as select * from t;

        View created.

        SQL> drop table t;

        Table dropped.

        SQL> select * from v;
        select * from v
                      *
        ERROR at line 1:
        ORA-04063: view "TEST.V" has errors

        SQL> select distinct name, type# from sys.obj$ where name like '_';

        NAME                                TYPE#
        ------------------------------ ----------
        V                                       4
        T                                      10

        SQL>

What are objects with "type = 10" in SYS.OBJ$? In the DBA_OBJECTS view it's excluded as "NON-EXISTENT", but there are a few objects of this type.