We leave aside isolated objects that are claimed to be fossilized siliceous spicules, because these objects have little morphological information content, and also the numerous claims of fossilized sponge-grade organisms from several parts of the world dating to about 555 Ma, close to the Precambrian/Cambrian boundary.. Virgin Islands Uganda Ukraine United Kingdom United States United States Minor Outlying Islands Uruguay Uzbekistan Vanuatu Venezuela Vietnam Wallis and Futuna Western Sahara Yemen Zambia Zimbabwe Zip / Postal Code SAN FRANCISCO SINGLES