Ok. Here is the test script to prove my point:

create table test_src (loc number primary key);

insert into test_src values (1);
insert into test_src values (2);
insert into test_src values (3);
commit;

create table test (loc number primary key)
organization index;

insert into test values (1);
insert into test values (2);
insert into test values (3);
commit;

create materialized view test on prebuilt table
as
select * from test_src;

select mview_name,container_name
from user_mviews
where mview_name='TEST';

select table_name,iot_type
from user_tables
where table_name='TEST';


Sergey