Large Machined Hole Above Oil Filter on '06 TSX -- Should there be something in / on it?

When doing my second oil change on our '06 TSX yesterday I noticed the just above the oil filter the block has a large machined and threaded
hole of about 1" diameter. It shines like untouched aluminum. I am wondering if something fell out of or off of there as it had not a bit of dirt in it even though the car has almost 7,000 miles on it now.
Is this just a mounting point for some option my car doesn't have?
Thanks for any clues!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file
Upload is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.