What do you mean, with a shell?

"Shelled" usually refers to some marine organisms and some terrestrial organisms, so it is named because its body surface is protected by hard shells, crustaceans or exoskeletons. These shells usually provide them with physical protection and support. Common crustaceans include turtles, lobsters, snails, shellfish and sea urchins.

In ancient culture, "shell" also has symbolic significance. For example, in the traditional culture of China, turtle shell is regarded as a symbol of immortality and wealth, which has beautiful meanings such as "Long life for Ju Chi" and "Chrysanthemum pond and moon". In Greek mythology, the clams born in Aphrodite were endowed with symbols of fertility and beauty. Their specific symbolic meaning depends on different cultures and times.

In the field of computer science, "shell program" refers to a program that can interact with people, and is usually called "shell". This program allows users to directly operate the computer and run programs. "Shell" is most commonly used in Unix-like operating systems, including Linux, Mac OS and BSD. Using shell program can complete the operation faster, which is suitable for some short and frequent tasks.