Fossil Sponges.

Sponges are multicellular, aquatic animals in the phylum Porifera. Their general body plan is a tube, open at one end and closed at the other. The external wall has pores through which water is drawn into the body, then interior channels circulate water through their internal structures. Sponges filter food and absorb oxygen from the water, then expel the water and waste through the large opening at the end of the body.

Two basic kinds of sponges were common in the ancient seas that once covered the Las Vegas area: spherical (or bag-like) sponges and elongate sponges. Both had multiple interior layers and appear in many sizes and shapes.

Sponges are common in the limestone mountains around Las Vegas. A good place to see them is along Fossil Canyon Trail in Red Rock Canyon National Conservation Area.