Leaves lacking a petiole are called sessile or epetiolate. The leaves are in opposite pairs, triangular and crenate, sessile or with short petioles. The leaves are generally petiolate or subsessile, rarely sessile. The leaves are sessile and sub-sessile, opposite, ovate, cordate at the base. The leaves may be petiolate or sessile. The leaves are opposite or whorled, and sessile. The leaves are simple, flattened and may be sessile or short petiolate. Scyphozoans generally have planula larvae that develop into sessile polyps. Sponges have a motile larval stage, which becomes sessile at maturity. The cauline leaves are much reduced and are short petiolate to sessile but not auriculate-clasping. Pedunculated polyps are more common than sessile ones. These include tunicates, mollusks and sessile Cnidarians. These were composed of enigmatic tubular and frond-shaped, mostly sessile, organisms. Space is a limiting factor for sessile invertebrates on rocky shores. The sessile plate-like stigmata lies on top of the ovary.