That shape can affect movement of clam-like
objects in waves has been demonstrated previously Clever, 1958; Lever et al., 1961, 1964, 1968).
Like many less exceptional deposits, the Burgess harbors mild-mannered mollusks, trilobites (the ubiquitous, armored "cockroaches" of the Cambrian seas) and clam-like brachiopods.
In 1968, Stefan Bengtson of the University of Uppsala, Sweden, described several early Cambrian specimens of the small, clam-like Mobergella, each with a neat round hole through the apex of its shell.
Paleontologist Mark McMenamin of Mount Holyoke College in South Hadley, Mass., notes that minute holes, or punctae, pepper the shell of the clam-like Mickwitzia.