Of course, as you may already have suspected, there are not only bongs made from glass or acryl. Most seasoned smokers are still familiar with those pretty ceramic pipes we had back then - they are probably the oldest kind of bong, predated only by coconut or bamboo smoking devices.
Ceramic bubblers are most often not as big as glass bongs or acrylic variants, and they come with a screw thread just like acrylic bongs, with aluminium downpipes, which are more easy to mount and use.
Another advantage is the special taste of ceramic bongs - some say, it is an acquired one, though. There is definitely some sense to it, but this is a rather individual point of view.
Thanks to the versatile material, ceramic pipes can be manufactured in elaborate shapes and in many colours. So you can find tons of pipes with individual design and shapes.