Survival of the FITTEST - is the theory that the strongest, fastest or most agile members of a species - will procreate and carry on the reproduction of that species.
most have shells
?
It depends, there is always someone who is very agile in hockey.
It is the most complex type of mollusks.
In the seas
Most are in water.
cephalopod
Most mollusks are free-living but there are a few that are parasitic.
The rockhopper is the smallest but, by far the most agile penguin which chooses to reside on rocky coastlines only throughout the austral summer months.
Agile means to move quickly and lightly; or to be nimble. In some cases this means tall, but not all the time. However, most tall people I have met are Agile.
The thin folded membranous tissue that envelops most of the visceral mass in mollusks is called the mantle. The mantle is common on all mollusks, including those that live in freshwater.