Black Lizard is a nickname for Barnard 138 dark nebula in the star rich area in constellation Aquila (Eagle). Actually this is not very well defined dark nebula, that hardly resembles this animal. If you increase contrast to almost maximum, then its shape is more obvious, however when someone wants to keep relative brightness all over the frame, then Black Lizard is not really black. Only few shades darker than surrounding star field. It is supposed to be about 2000 light years away, and can be spotted with medium sized binoculars under really dark sky. Any light pollution or any higher magnification will make this dark dusty invisible. Many dust nebulae are really elusive, and you need to know what to look for to identify them.
There are few more dark nebulae in the frame – two more from Barnard catalogue and several from LDN catalogue – you may follow them at the map below (map comes from http://www.forumastronomiczne.pl/index.php?/topic/8715-obiekt-tygodnia-7102015-barnard-138/ ). And also a few shining deep sky objects were captured – two globular clusters and PK 36-1.1 aka Sh2-71 planetary nebula – tiny reddish egg shaped blob in the upper right frame part.
I captured data to this image during 2018 summer holidays in Anticiana, Toscana. I used travel setup with Samyang 135 telephoto lens and QHY163M camera on Smart EQ mount.