Trichomes on plants are epidermal outgrowths of various kinds. The terms emergences or prickles refer to outgrowths that involve more than the epidermis. The sides of the foot have evolved into parapodia, fleshy winglike outgrowths. Also bony outgrowths, called osteophytes, are formed at the joint margins. Lateral outgrowths on the body of nudibranchs are called cerata. These are small, spiny outgrowths of the stem, lacking their own vascular supply. Nerve fibers are outgrowths of nerve cells. Insect wings are adult outgrowths of the insect exoskeleton that enable insects to fly. In some multicellular animals, offspring may develop as outgrowths of the mother. In annelids, parapodia are paired, un-jointed lateral outgrowths that bear the chaetae. They all are outgrowths of the exoskeleton and their cavities contain blood. The exoskeleton of "Eurypterus" is often covered with small outgrowths known as ornamentation. The anthers have awl-shaped outgrowths on the top. They increase in number by outgrowths from the original tubules. At the same time, developing neurons send out axon outgrowths that contact their target cells.