what needs contact to smooth over long periods of time?
oxygen soil an object h2o rivers quartz cartilage bamboo
A B C D E F G H
Type of Rocks Salt, quartz and basalt are decent types of aquarium rocks.
contact between quartz over long periods of time causes it to smooth
what needs contact to smooth over long periods of time? (A) oxygen (B) soil (C) an object (D) h2o (E) rivers (F) quartz (G) cartilage (H) bamboo