Whether this last common ancestor of mollusks and entoprocts bore (seven) shell plates (as is assumed for the ur-aculiferan), or whether such dorsal armature constitutes an invention of Mollusca alone, remains unknown and first requires reconstruction of the last common ancestor to all mollusks before further assessments can be made.
A few phoronids bore into shells or calcareous rocks, making distinctive holes.
The presence of protease inhibitors in an external structure such as the molluscan shell may provide the shell with an ability to resist the digestive enzymes secreted by fouling organisms and predators that would dissolve and bore through the shell, for example natacid gastropods [ 34] polydorid annelids [ 35] and sponges [ 36].
The whelk needs a few hours to penetrate the shell and thus living in the littoral zone is an advantage to the bivalve because the gastropod can attempt to bore through the shell only when the tide is in.
Some Penitella and Diplothyra species bore into the shells of other mollusks, particularly oysters and abalone.
Some sponges bore into the shells of bivalves, gastropods, and the colonial skeletons of corals by slowly etching away chips of calcareous material.
Some skeptical residents point to the fact that dud shells bore all-too-obvious Japanese markings and that a Marine detachment had pulled out of nearby Goleta just days before.
As humans, the twins, Wanda and Pietro Maximoff, are orphans, whose parents fell victim to a shell that bore the inscription "Stark Industries" — Iron Man's technological empire.
The concentration polarization phenomenon is mathematically described using the film theory, while the Hagen Poiseuille and Ergun equations describe the pressure drop in the fiber bore and on the shell side of the fiber bundle, respectively.
The seashore accents are subtle: The carpet bears a nautilus shell pattern, the bedside lamps have a golden shell base and local artists and Ringling School of the Arts students create the framed pieces (our room had an image of a canoe on a washed-out beach).
