Like the rocks of the Precambrian Eon, rocks of the Cambrian Period in Kentucky are poorly understood, and for the same reasons. What little we know about the Cambrian below the surface tells us that Kentucky was under seawater for a period of time, but there were also times when land was present. Based on the Cambrian in other areas, we can surmise that there was no land life except for perhaps bacteria, fungi, algae, and lichens (algae and fungi living together). The seas, however, may have been teeming with life; sea plant life would have included bacteria and algae, and animal life would have been entirely composed of invertebrates such as trilobites, other arthropods, brachiopods, sponges and sponge-like animals, and a host of unusual animals (now extinct) similar to those known as the Burgess Fauna. The Burgess Fauna was made famous by a series of excellently preserved fossils found in the Cambrian Burgess Shale in Canada. Early forms of mollusks, echinoderms, and small fish-like worms that later gave rise to conodonts and vertebrates may have existed during the Cambrian in Kentucky as well.