What you were probably seeing were Chironomid
pupa. They are the lake-dwelling cousins of stream-dwelling midges and are usually present in tremendous numbers and fish will wolf them down like crazy as they ascend the water column to hatch.
They can range from 1/4" to over 1" long and come in every color under the rainbow, although most will have varying degrees of red in them.
Here is a pic of a typical Chironomid - note the bright white gill plume... this is a trigger point for the fish that you will see exaggerated in almost all successful patterns.
Here is a row of "Snow Cones" in my midge box. Easy tie and yet amazingly effective when the fish are chomping on chironomids. Just float them below a strike indicator set at - or just above - the level of working fish. A moveable strike indicator helps in case you need to adjust the depth to find that sweet spot.
Here is another one that works well when sight casting to shallow working (cruising) fish. It's called the Rojo Midge and you can find it on Charlie Craven's website. I tie them in olive (seen here) and red.