The mixture was then boiled until it thickened. Collenchyma tissue is composed of elongated cells with irregularly thickened walls. Puddings are thickened with starches such as corn starch or tapioca. Custards are cooked and thickened with eggs. Blancmange is sometimes thickened with gelatin or isinglass, sometimes with starch. The water was boiled until it thickened and turned black. Ichthyosis is a family of genetic skin disorders characterized by dry, thickened, scaly skin. The stems of these pinnate leaves are thickly thickened at the bottom. Phocids have thickened mastoids, enlarged entotympanic bones, everted pelvic bones and massive ankle bones. A stem tuber forms from thickened rhizomes or stolons. It may be thickened with eggs or flour. The leaf margin is slightly thickened and usually serrated. The dish is thickened with palmyra root flour. Sometimes the cream is thickened with flour before being added to the soup. Sauces should be thickened after pressure cooking.