A green warning construction sign.
<a href="//commons.wikimedia.org/wiki/User:HuBoro" title="User:HuBoro">HuBoro</a>
Own work (recolor from <a href="//commons.wikimedia.org/wiki/File:Ambox_warning_blue.svg" title="File:Ambox warning blue.svg">File:Ambox warning blue.svg</a>)