Movie S1.

Dynamics of the outer protective envelope during the earliest stage of chamber formation in Amphistegina lessonii d’Orbigny. This time-lapse video presents the dynamic behavior of the outer protective envelope (OPE) with fingerlike protuberances attached to the substratum. Start of time-lapse movie: 00:55:24 from the onset of chamber formation; recorded: 00:36:22 (hrs:mins:sec.); real time/video time (both in seconds): 2182/5 = 436 times faster than real time. Merged fluorescent and transmission light (SiR-actin/aF+TL); fluorescent light only (SiR-actin/aF); autofluorescence (aF).