Rocks ARE great. Unless they are:
1. Intelligent, hostile, murderous rocks. ( Like on Star Trek, the original series. ) Or,
2. High explosive rocks that go off when a Security guard trips over them. ( Also on Star Trek the original series. ) Or,
3. The huge rock, ( About the size of Coventry Cathedral. ), that Arthur Dent and Ford Prefect were trapped under, with no hope of rescue. ( In the Hitch-Hiker's Guide To The Galaxy. ) Or,
4. Stupid, hostile, murderous rocks. ( Like on Galaxy Quest. )
Just thought a note of caution was called for.......!
