Override Activity Stream output

In my template design i am customizing how the activity stream module will look.
This involved the overall aspect of the activity stream module aswell as individual aspect of the stream items shown into this module.

I completed the design and now i am looking for a way to implement it ....

So far, i created an override folder for the EasySocial Stream Module into my template location

/templates/my_template/html/mod_easysocial_stream/default.php

and inside this module override i tried to customize the output of the stream but i noticed that stream items are outputed with the code shown below

<?php echo $stream->html();?>

So, the question is: Where i can override the look and feel of stream items for this module ? Thanks !!!