Attention, San Franciscans! If you're tired of paying outragously high home rental fees, then I've got a deal for you!
The BBC 2 program Natural World tells us about the unique relationship between the pearlfish and the sea cucumber. The sea cucumber is a "walking colon"--an animal that sucks in sand along the ocean floor, then squirts waste out the back end.
To the pearlfish, that back end is attractive. In search of a good home, it finds a sea cucumber butt and slides right in. In fact, it's such a comfy abode that it invites other pearlfish to join it. Everyone is welcome to crash at the pearlfish's pad.