Signal transmission and covert prepattern in the metamorphosis of Hydractinia echinata (Hydrozoa) Schwoerer-Böhning, B.; Kroiher, M.; Müller, W.A. Roux's Archives of Developmental Biology the Official Organ of the Edbo 198(5): 245-251 1990 0930-035X 10.1007/bf00377390 https://eurekamag.com/research/060/248/060248770.php