Shelley the Turtle appeared on Sesame Street primarily during the late 80s and early 90s. Shelley was a friendly but slow turtle.
He made an appearance in season 30, with the same voice but referred to in the dialogue only as "The Turtle," where he attempted to join the menagerie on Old MacDonald's farm. He recently appeared on sesamestreet.org, appearing with Elmo in a day called Mommy Time.
The puppet later appeared with a new shell as Seymour.