Across
1
Biological catalyst
4
Magnetic metallic element
6
Reddish electrical conductor
7
Second lightest element
8
Tissue that contracts for movement
9
Substance with pH below 7
10
Ball of burning gas in space
12
Preserved remains of ancient life
13
Element found in all living things
Down
2
Compound containing oxygen
3
The Red Planet
5
Blocking of light by a celestial body
11
Path of a planet around the sun