The connection of blastomeres of sea urchin embryos by filopodia.
D003593:Cytoplasm; D004447:Echinodermata / Q000166:cytology*; D004625:Embryo, Nonmammalian / Q000166:cytology*; D005314:Embryonic and Fetal Development; D008854:Microscopy, Electron; D008858:Microscopy, Phase-Contrast