Here's a Belizean bug that doesn't look like much:

I'm serious. In the field the insect looked like so little I thought it merely debris in a disorganized spider's web. I didn't see the faint outline of a young assassin bug until the debris shuddered, ever so slightly.

The dramatic contrast of the above image is only because I've removed the animal and its clever camouflage from its favored habitat. Such transplants, for better or worse, are a common trick of insect photographers to bring out the glamour of insects whose primary defense is hiding in plain sight. The insect is considerably less obvious in situ:

What's this little predator doing in the web of another predator? Presumably, hunting. Some emesines, especially those in the genus Stenolemus, are spider specialists. While I can't say much about the species pictured here, at least some spider assassins lure in their prey by mimicking the movement of trapped insects. When the spider approaches... Bam!

(video source: Assassin bug uses aggressive mimicry to lure spider prey, Anne E. Wignall and Phillip W. Taylor, Proceedings of the Royal Society B, 2010, doi: 10.1098/rspb.2010.2060 )