These rotifers make beautiful reddish-brown tubes for their "homes". (see http://www.photomacrography1.net/forum/ ... php?t=1330)
When I first saw them I wondered where the nearly perfect spherical "bricks" came from. After watching for a while I saw the answer. At the back of the head is a socket where each spherical "brick" is rolled from detritus that is collected as the rotifer feeds. In the top image you get an overview of the location of this socket, as you can see another brick nearing completion. The lower photo shows an even closer view. The "ball" is constantly rotated around quite rapidly whenever the cilia on the corona are in motion. (In these photos the motion has been frozen by the electronic flash illumination.) As more detritus is added, the ball grows in size. When completed it is added to the tube. The right panel in the lower photo shows a detailed close-up of part of the constructed tube.
Top photo taken with 40X objective, bottom two with 100X. Canon 10D. Brightfield illumination with electronic flash,
