I recently came across this issue in both an 8.1.7.4 database and a 9.2.0.5 database. I created a table based off an object. The table showed up in user_objects as object_type='TABLE', but did not show up in user_tables. Does anybody have an explanation as to why this is?

Code:
jeffh@dev920.us> create or replace type money_t as object
  2  (
  3     amount number,
  4     currency varchar2(3)
  5  );
  6  /

Type created.

Elapsed: 00:00:00.06
jeffh@dev920.us> create or replace type moneyhistory_t as object
  2  (
  3     id number(10),
  4     price money_t
  5  );
  6  /

Type created.

Elapsed: 00:00:00.07
jeffh@dev920.us> create table moneyhistory_o of moneyhistory_t (
  2     id not null,
  3     price not null,
  4     constraint moneyhistory_pk
  5        primary key (id)
  6  )
  7  object identifier is primary key;

Table created.

Elapsed: 00:00:00.12
jeffh@dev920.us> select object_name, object_type from user_objects;

OBJECT_NAME                    OBJECT_TYPE
------------------------------ ------------------
MONEYHISTORY_O                 TABLE
MONEYHISTORY_PK                INDEX
MONEYHISTORY_T                 TYPE
MONEY_T                        TYPE
SYS_YOID0000061754$            TYPE

Elapsed: 00:00:00.02
jeffh@dev920.us> select table_name from user_tables;

no rows selected

Elapsed: 00:00:00.01
jeffh@dev920.us> desc MONEYHISTORY_O
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 ID                                        NOT NULL NUMBER(10)
 PRICE                                     NOT NULL MONEY_T