1 These can be two Excel files or an Excel File and a Microsoft Word file for example. 2  Press and hold down the Alt key on the keyboard. 3  Press and release the Tab key on the keyboard without letting go of the Alt key. 4  The ALT-TAB Fast Switching window should appear in the middle of your computer screen. Open at least two files in Windows. 2  These can be two Excel files or an Excel File and a Microsoft Word file for example. 3  Press and hold down the Alt key on the keyboard.
Merge this question into. Split and merge into it. Answer by Quirkyquantummechanic. Confidence votes 77.6K. Almost all of a mollusk shell is composed of calcium carbonate. It may take a few different forms and thereby appear differently, but CaCO3 is the main material in the shell.
In general, mollusks have a soft body with a discernible head and foot region, and a hard exoskeleton in the form of a shell or plate. Mollusks are ubiquitous in both marine and terrestrial environments, and range in size from smaller than one millimeter to twenty meters long. There are eight classes in the phylum Mollusca. The focus of this discussion is on three of the five classes in the subphylum Conchifera, or shell-bearing mollusks. Three classes in Conchifera with an important presence in the Gulf of Mexico are Gastropoda, Cephalopoda, and Bivalvia.