Hi Rick,
Owh, Now I know, the code of calendar can be found in this file:
JoomlaFolder/components/com_easyblog/themes/origami/blogs/latest/default.main.php
which is this code:
<div>
<div class="eb-post-calendar" itemprop="datePublished" content="<?php echo $post->getDisplayDate('created')->format(JText::_('DATE_FORMAT_LC4'));?>">
<div class="eb-post-calendar-m">
<?php echo $post->getDisplayDate($this->params->get('post_date_source', 'created'))->format('M');?>
</div>
<div class="eb-post-calendar-d">
<?php echo $post->getDisplayDate($this->params->get('post_date_source', 'created'))->format('d');?>
</div>
</div>
</div>