Can you please post a picture of the bottom of the piece? Can you please post a close up picture of the pieces. Is there any variation in the color/texture? (if totally consistent most likely man-made.)
I would search a bit more before you do a needle test. You may want to search using the term "tesselated bone" camel, camel with riders, etc. If it is - then it would be worth a pretty penny. You will find many pieces made using camel bone itself!
Also, there is a "Hot Needle Test" that you can do to determine if it is bone/ivory versus plastic/celluloid.
HOWEVER, where you place the hot needle will cause permanent damage so you must choose your area carefully. I would choose this as a last resort.