Does anyone know if there is a Turtle daoist internal practise?

I've heard of the ~5 minute long turtle breath, but that's all in my limited experience

There is one I remembered from the Great Dao book by Stephen Chang...

The Turtle internal exercise to stimulate the nervous system. Through that basic practice, one can find the methods in it that loosen the spine, retain energy(no leaking out the hand/fingers), cultivating some compression in the lower dantian, activating the chest dantian, and stimulating the third eye and crown.. hehehe
Ofcourse that isn't in the book

Fun stuff!

Peace,
Lin

We have a tortoise form in Hsing-i Chuan. It's one of the simpler forms, but it teaches you to link the six harmonies, and thread the Chi through the body very effectively. Unfortunately I cannot find a clip for you, but perhaps this information will lead you in a direction that bears fruit.

Bodhi

That made me think of the 'turtle neck' exercise I learned in some of Chia's material. It seemed related to a wind path MCO circulation exercise...

We practice two qigong exercises called turtle and crane breathing. The basically consist of a rotational movement incorporating the head, neck, and upper spine in forward and reverse directions, coordinated with breath and intention. I'll try to find out where my teacher learned them.