- [Narrator] They are small gifts from the sea beautiful seashells that delight with their intricate form and stunning colors.

- [John] We all go to the beach and find these just exquisite shells.

It's a very common hobby, especially here in Florida.

- [Ruediger] We use the word seashells sea shells kind of for two different things.

One is the shell itself, (the skeleton) and the other one is essentially the group name for shelled marine mollusks, mostly snails and clams.

- [José] The shell is there from minute one, very microscopic at that point.

And as the body of the mollusk grows, it will add more and more shell material, making the shell larger.

- [José] The shapes are super varied and there's a lot of engineering that goes into that to make the shells resilient and strong.

- [Ruediger] This is It's this external skeleton, and it's is permanently attached to the living soft body inside.

In snails, it's usually one muscle.

In clams, it's often two or more.

- [Narrator] There is an incredible diversity of species.

- [José] Mollusks, although they are kind of a poorly known group by regular folks out there, they're one of the largest groups of animals on the planet.

They are found everywhere.

- [Narrator] Scientists estimate there are approximately 50-thousand shelled marine mollusks that have been described to date, with more than one new species being named every day.

- [José] We just barely scraped the surface.

- [Harry] Some people estimate that only half of the known species have been described which is unfortunate because some are going extinct as we speak as are altered, and under habitats are altered under the pressure of human populations.

- [Linda] The more you appreciate something, the more you'll try to protect it.

- [José] Mollusks and their shells, their lives have been intertwined with humans since probably the dawn of human life.

And I think the first connection is food.

- [Ruediger] They have been used as tools or sacred objects in both daily life and in religion, in many different cultures.

- [Narrator] Even today, their elaborate shapes and symmetry are often reflected in architecture, fashion, instruments, and jewelry.

But how do the living animals spend their lives?

And what is their role in the ecosystem?