Whilst observing my aquatic plant specimen in its tray during November, I noticed movement of little 'twigs' on the bottom of the container every now and again. I isolated one and observed it at close quarters in a white frisbee. It was a worthwhile endeavor - this is the creature I saw foraging:
It's a beautiful caddisfly larva - so distinctively striped as to look fierce! It drags a little self-made protective case around with it as it seeks food (detritus and organic matter). Every now and then it protrudes from its tube to grab something to ingest, but it never leaves the casing entirely. Its abdomen is quite long, very similar to that of a caterpillar, but most of it stays hidden in its casing.
Here's a photo from Encyclopedia Britannica that shows an Adult caddisfly.