Body organs make up the visceral mass and are protected by the __ which secretes the __

It is the mantle that protects the visceral mass making up the body organs. In addition, the mantles secrete a specific compound named calcium carbonate and conchiolin, which are very essential for the creation of shells protecting the organism against its harsh environments.

A pattern of gradual change in a condition, output, or process, or an average or general tendency of a series of data points to move in a certain direction over time, represented by a line or curve on a graph.
two trends are the "boho" style, someone can start an "ethnic" store 
"electronic music" someone can start a new club because of the increase of clubbers