How do trace fossils provide evidence of past life?​

body fossils are evidence of what was living where and when. Trace fossils are valuable because they "animate" the accident animals or plants by recording a moment of an organisms life when it was alive.

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.