But it's such a huge change that it sometimes feels like I'm floating through space with no solid ground beneath me.

Not like the hard plastic one in front of you now.

They often provide the only hard surface and structure in the midst of a sandy bottom, something many sea creatures need.

The bark is the hard skin on the outside of a tree. It protects the tree.

Existing scanning systems, which capture a print in two dimensions, require the pressing or rolling of a finger onto a rigid plane.