The little containers are for baby tarantula (im talking TINY, half the size of a dime)
Tarantula live in pretty small area's in the wild, rarely do they venture much outside of their den, they can go months and months without eating, some can go years. In larger tanks, Tarantula sometimes stay isolated and don't move much at all, since all Tarantula live in either Burrows, Holes in trees/wood or in small crevasses in tree's surrounded by web they feel comfortable in smaller tanks. Usually when you put a Tarantula in a smaller enclosure it will explore more, rather then sit in its burrow or in the corner.
Some spiders dig, some spiders are terrestrial (Live ON land, not really in it) and some are arboreal (Live in trees) each tank is specifically setup for each spider, you can see the difference in them
And lastly, the first thing I should have said in the thread was, this is not my room, I just like it. So no close ups