Flood stealth form
From Halopedia, the Halo wiki
The Flood Stealth Form was a Flood Purestrain form that was originally to be featured in Halo 3. Like the Stalker Form, it excelled in the art of stealth to defeat the enemy, and was the only purestrain form to be able to use weapons with the aid of two, four-tentacled hands.
The stealth form was seen in The Art of Halo 3, though it was cut from the retail version of Halo 3.