Because it's black on a black back ground. I remember asking myself that same question. I think that I bought it to see what it was and I already had them both. xD
Here is a video I found real quick. Both drop from collections and briefings if I am not mistaken. https://dcuniverseonline.fandom.com/wiki/Black_Energy_Tendrils The other one is called Blight Corruption ( Wall ) https://dcuniverseonline.fandom.com/wiki/Blight_Corruption_(Wall)
