I understand this to mean that passive Wisdom (Perception)—and even Searching—will never reveal a roper for what it is as long as it holds still. Its Stealth skill comes into play only if it's moving. Thus, a stationary roper takes its opponents by surprise, as long as its eye is closed and its tendrils retracted until it strikes.

an unsolved crime

Other Californiana and Americana includes some grand costumes of the early days given by the Ladies' Museum Society (a kind of feminine auxiliary to the gallery) […]

Drops are often considered the same as windfalls, and some people insist that any fruit that has fallen to the ground—no matter for how short a time—should not be used for making cider. […] Drops, on the other hand [unlike windfalls], are fruits that have sat around on the ground for a longer period of time—typically a day or more.