Question: Why is the "shusher" a rock instead of a egg?
Answer: The in universe reason is that it is weird and alien. The story telling reason is so Smek can clobber other Boovians with it.
Home (2015)
2 questions
Directed by: Tim Johnson
Starring: Steve Martin, Jennifer Lopez, Rihanna, Jim Parsons
Continuity mistake: When first arriving on Earth the aliens do a clean up of things not needed, one of these being toilets, then in a scene minutes later you see the main alien character brushing his teeth with a toilet brush standing next to a toilet. (00:05:45 - 00:07:00)
Answer: Gorg was tracking the "shusher"