Spot the difference?

http://www.yellowbridge.com/chinese/character-stroke-order.php?zi=龜

http://commons.m.wikimedia.org/wiki/File:龜-order.gif

There are at least two more different versions I've seen. On Pleco the legs traverse the the middle but are not joined up with the shell. And my writing app tells me to write the shell on the right before the legs. Bizzare.