Hi Lazaruz,
in the link_to call, when you only provide a variable, by rails
conventions the object's id value will be used and the show method
will be called.
fyi there were actually two correction I had to make in the javascript
code, in addition to what I mentioned earlier, I also has to change
jQuery method "ajaxSuccess" to use the "on" method like this.
$('.delete_pony').on( 'ajax:success', function() {