The reason for the turtle (tu) in memory of Steve Irwin

For the past one week, many people had put the thing on thier MSN messager in memory of the late Steve Irwin. Do you know what's the meaning of that turtle?

I've ask many people, and the answers are often ''oh...that turtle, becos there's no crocodile emocon... turtle belongs to the reptile family, so...'', ''I'm not sure, I'm just following what others do'', but the actual reason is that it represents the new species of Australian turtle which Irwin discovered and named after as ''Elseya Irwini''.Thus, the turtle emocon was used to commemorate his findings.