Why did Ruby on Rails' URL Helper put a period in my URL?

I have the following code in my view (RoR 4):

tbody
  - @order_submissions.each do |order_submission|
    tr
      td = order_submission.id
      td.table-actions
        span = link_to "Show", order_submissions_path(order_submission.id)

---

td = order_submission.id 

successfully displays as the ID number (533ab7337764690d6d000000)

But...

order_submissions_path(order_submission.id) 

Creates a URL that comes out as:

order_submissions.533ab7337764690d6d000000

I want it to be

order_submissions/533ab7337764690d6d000000

Where did that period come from?

This is my route:

get 'order_submissions/:id'         => 'order_submissions#show'

And when I run rake routes I get:

GET    /order_submissions/:id(.:format)        order_submissions#show

The (.:format) is probably what's messing it up but I don't know why. I just want it to put a slash in there.

If I change my code to this it fixes it:

 span = link_to "Show", order_submissions_path + '/' + order_submission.id

But that's a really, really stupid workaround.

EDIT: Here are my routes:

   get 'order_submissions'             => 'order_submissions#index'
   get 'order_submissions/new'         => 'order_submissions#new'
   post 'order_submissions'            => 'order_submissions#create'
   get 'order_submissions/:id'         => 'order_submissions#show'
   get 'order_submissions/:id/edit'    => 'order_submissions#edit'
   patch 'order_submissions/:id'       => 'order_submissions#update'
   get 'order_submissions/:id/delete'  => 'order_submissions#delete'
   delete 'order_submissions/:id'      => 'order_submissions#destroy'

The order_submissions_path (plural) points to /order_submissions. It takes two arguments, the first being the format for the request (e.g. html). Your ID is being passed in for this argument, leading to the resulting URL you're seeing.

You actually want the singular path helper, order_submission_path, which accepts an ID as the first argument.