Here is a picture of a giant tortoise called Grk:

He lives in a sanctuary run by the Nature Protection Trust of Seychelles. When this photograph was taken, he was only a few months old. If he's lucky, he might live a hundred and fifty years, or even more.

In Operation Tortoise, Tim and Grk go on holiday to the Seychelles. They meet lots of giant tortoises - and rescue them from an evil billionaire who is planning to kill them.

Here are three more photos of Grk. When these were taken, he was almost three years old.