MySQL obtém string(s) entre dois # / múltiplos pares de #

<?php
    $s =  'This is #important# and needs to elaborated further. Remember to buy #milk before coming home#';
    for($i=0;$i<strlen($s);$i++)
        if($s[$i] == "#") {
        $i++;
        $str="";
        while($s[$i]!='#') {
            echo $s[$i];
            $i++;
        }
        echo '<br>';
    };
    ?>