Renewal in Nucella canaliculata calls for a crowd. Winter and spring aggregations of channeled dogwinkles, that’s their common name, copulate and lay eggs over a several week period. In the finale, females deposit eggs in straw-colored vase-like cases.
I took the photo above on April 19, 2018. If I am interpreting it correctly, the cases, each containing twenty or more fertile eggs, are the collective production of the females over several days.
Marko, P. B., A. L. Moran, N. K. Kolotuchina, N. I. Zaslavskaya. 2014. Phylogenetics of the gastropod genus Nucella (Neogastropoda: Muricidae): species identities, timing of diversification and correlated patterns of life-history evolution. Journal of Molluscan Studies, 80(4): 341–353