Oracle: how to query a table if I know only its (non-default) tablespace?
Given your DBA_TABLES query, you have the following:

Owner (Schema Name): EXAMPLEOWNER

Table Name: MYTABLE

The SYSTEM user will not just be able to select from MYTABLE unless there is a Public Synonym pointing to it.

So, to select from the table you have to fully qualify the name by prefixing the table with its schema:

SELECT * FROM EXAMPLEOWNER.MYTABLE;


Note that tablespaces are simply the place the object is stored in, and have no bearing in DML queries.