<?php

$sample = 'aaa <object>1</object> bbbb <object ccc></object> ddd eee fff <object></object>';
preg_match_all('/(<object.+?<\/object>)/', $sample, $xxx);
print_r($xxx);


/*

REZULTAT:
Array
(
    [0] => Array
        (
            [0] => <object>1</object>
            [1] => <object ccc></object>
            [2] => <object></object>
        )

    [1] => Array
        (
            [0] => <object>1</object>
            [1] => <object ccc></object>
            [2] => <object></object>

        )

)



*/