Sandbooooox
http://www.dl-digital.com/images/Bugs_Spiders/DD2_2171-Green-Scarab.jpg
Contained in a standard terrarium, fed on a regular schedule. Any video monitoring is only in black-and-white, and anyone entering the enclosure must wear tinted glasses to filter out the true color.
Beetle with no other anomalous properties, diet, or apparent anatomy. Every morning (determined to occur at sunrise in Cairo, and specifically when the sun strikes a certain spot in the Al-Matariyyah neighborhood) it changes color. No pattern has been discerned. Discovered by Foundation agents upon following rumors of a child charging people a small fee to watch the insect's transformation every morning. Considered not even a proper SCP, just an anomalous object, until Incident BBB, when it was reclassified as Safe.
Incident AAA: Researcher A, sent to clean and feed the entity's cage, noted that its color was a "sort of sickly puke green," and reported feelings of unease and nausea. Researcher B also entered the enclosure to examine the insect, and reported no ill effects.
Incident BBB: Researcher C, sent to clean and feed the entity's cage, reacted with extreme distress and alarm upon entering the enclosure.
C: That's not… that's not a real color.
D: What's going on in there, C?
C: The bug, it's changed to some kind of… orange-green… no, it's more of a… purple-yellow? Like a green-blue, but not /between/ green and blue, it's like it's all green and all blue all at the same time.
D: C, you're not making any sense. What is it, teal?
C: No, no, it's so much worse than that. Just come in here and see for yourself.
D: That doesn't sound like a good idea, at least not until we know what's going on.