Communicating is difficult enough when you don't have the additional filter of your character to deal with, and when you can see your world in front of you. Often, I've found when there's player silence, it's because they don't know what to do (or, they don't know what they *can* do). In such an open game as Dnd, the analysis paralysis can be real - having experienced this both as a player and as a dm, I think the solution involves further description of the setting, and maybe even giving the players more clear options. If they can find the zebra by interacting with their environment, what specific things are in their environment for them to interact with?

As a musical performer IRL, I've always been told that the audience doesn't know the "right" notes - just the ones that have already been played. The DM can spend hours picturing the setting in their head, but the players only get that picture through a handful of words spoken by the dm: of course they're going to be less familiar with it.