Turtle is fine. So's JT, JTurtle, or pretty much anything else... I always shorten people's names too. ;-)

(Hey, I switch default icons a lot. Although this is indeed an excellent one. Maybe I'll get tired of it before it gets like JJ's icons: impossible for anyone else to use without inducing mental whiplash! XD)

'Sides, you could just use it too. Then we could have massive conversations where we confused the heck out of everyone. ;P