Sample of reusable block in Gutenberg

gutenberg.html

<!-- wp:paragraph -->
<p> Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vivamus 
  tincidunt nunc vel consequat dapibus. Pellentesque aliquet felis 
  nulla,  sit amet efficitur mauris finibus in. </p>
<!-- /wp:paragraph -->

<!-- wp:block {"ref":50} /-->

<!-- wp:heading -->
<h2>Lipsum dolor sit</h2>
<!-- /wp:heading -->

<!-- wp:list {"ordered":true} -->
<ol><li>Massa dictum</li><li>Neque vitae</li><li>Porta ut morbi eu</li></ol>
<!-- /wp:list -->

<!-- wp:image {"id":47} -->
<figure class="wp-block-image">
  <img src="http://mysite.com/wp-content/uploads/coffee-cup.png" alt="" class="wp-image-47"/>
</figure>
<!-- /wp:image -->

<!-- wp:paragraph -->
<p>Vivamus eleifend, erat eu  scelerisque condimentum, justo dui dictum neque, rutrum 
  ornare est leo  vel erat. Donec auctor tempor scelerisque. In dapibus elit velit, vitae
  tincidunt urna porta ut. Morbi eu euismod massa. </p>
<!-- /wp:paragraph -->