The word I am looking for would mean something similar to “not what it seems”

How about camouflage -- which humans copied from nature where it is known as "protective coloration".

Nature had long since learned the value of camouflage and had clothed the animals so for their protection. Many examples among insects may be readily called to mind and the concealing coloration of the ground-dwelling birds, such as the Grouse and Nighthawk, is familiar. Whether the same principle can be applied to all birds, including those of brilliant colors might be of some question. We must remember however that the birds are not colored to be protected from us. We have, to some extent, become enemies of theirs, but they were not adapted for that contingency. We must interpret their coloring as far as possible in terms of how their enemies see them or how they see their enemies.

http://www.nps.gov/mora/notes/vol10-7a.htm

Of course, we all know about chamelons which can change their color.

But I remember reading about a moth which looks like a Monarch Butterfly. Apparently, this moth's natural predators do not favor the taste of Monarch Butterflies, so this moth has adopted the costume of a Monarch Butterly to fool its predators.

NOTE: This is known as "deceptive colaration" and it's the Viceroy Butterfly I'm thinking of which mimics the Monarch, not a moth.

The viceroy and monarch were once thought to exhibit Batesian mimicry, where a harmless species mimics a toxic species. Studies conducted in the early 1990's suggest that the viceroy and the monarch are actually examples of Mullerian mimicry where two equally toxic species mimic each other to the benefit of each. Just goes to show you there's always something new to discover in the natural world!

http://www.nhptv.org/natureworks/viceroy.htm

Same thing with your framed picture protecting your jewelry, insearchof.

However pretty the picture, the real treasure is always inside.* :)

It occurs to me that this phenomenon is really the opposite of trompe de l'oeil. Trompe de l'oeil fools us into believing the treasure is on the outside.

There is also "disruptive coloration", "aggressive mimicry" and "cryptic mimicry".

http://www.nhptv.org/natureworks/nwep2a.htm

We humans seem to learn all our best tricks from lesser species. Maybe we're not as smart as we think we are. :)

* BTW this isn't an original thought, so I don't want to take credit for it. In fact, for most people it's so common it's a platitude. A platitude is a lot like trompe de l'oeil, now that I think of it.