how to echo all tables that start with

I am trying to get all tables that start with a prefix

   global $wpdb;
   $tables = $wpdb->get_results("show tables like 'pro_hist%'");
   echo '<pre>';
   print_r($tables);
   echo '</pre>;

and this works, it gives me this answer

Array
(
    [0] => stdClass Object
        (
            [Tables_in_plugin (pro_hist%)] => pro_hist1579
        )

    [1] => stdClass Object
        (
            [Tables_in_plugin (pro_hist%)] => pro_hist1580
        )
)

but how can I echo this out?

if I do print_r($tables[0]) I get this result

stdClass Object
(
    [Tables_in_plugin (pro_hist%)] => pro_hist1579
)

Now I wanted to echo "pro_hist1579" ?