The phrase "a single shell" is correct and usable in written English.
It can be used when referring to one individual shell, often in contexts related to marine biology, construction, or metaphorical uses.
Example: "The beach was littered with various shells, but I found a single shell that was perfectly intact."
Alternatives: "one shell" or "a lone shell".
The gunshot left a single shell on the Midtown pavement.
A single shell casing was recovered at the store, he said.
This result might make sense if the authors had observed the emission from a single shell of ejected matter.
As we looked over his shoulder, Baber hit a red button on the remote control, firing a single shell into the hillside.
A single shell casing was recovered from the scene, the police said, but no firearm was found and no arrests were made.
A single shell from the bazooka, a portable rocket launcher used by, the Army, arced across the river from Queens and fell harmlessly about 200 yards from shore.
In the present work it has been investigated if such level of adhesion strength is sufficient to restore the component's stiffness in the cases when stiffness has been compromised by substituting a twin-shell large-thickness drawing-quality-steel design of a prototypical BIW component with a single-shell lower-thickness high-strength-steel and polymer-hybridized design of the same component.
The latitude of the ionospheric pierce point (IPP) for the different satellite-to-receiver links was calculated every 1 min assuming a single-shell ionospheric model at an altitude of 350 km.
A single-shell forward model was used (Nolte, 2003).
Leadfields were calculated for each participant based on a single-shell model (Nolte 2003) of the brain.
The forward model was derived from a single-shell model (Nolte, 2003) fit to the inner skull surface of the inverse normalized SPM template.
