where did the term olly olly oxen free come from
Olly olly oxen free Cassidy and Hall write that the phrase may be derived from all ye, all ye outs in free, all the outs in free, or possibly calling all the "outs" in free; in other words, all who are out may come in without penalty.[2] Various calls used for such purposes have gone by the collective name of "ollyoxalls" in some places.[3] Tukey and Rowell speculate that the phrase may be a corruption of a hypothetical and ungrammatical German phrase alle, alle, auch sind frei (all, all, are also free).[1]
Oxygen In nature, free oxygen is produced by the light-driven splitting of water during oxygenic photosynthesis. According to some estimates, green algae and cyanobacteria in marine environments provide about 70% of the free oxygen produced on Earth, and the rest is produced by terrestrial plants.[64] Other estimates of the oceanic contribution to atmospheric oxygen are higher, while some estimates are lower, suggesting oceans produce ~45% of Earth's atmospheric oxygen each year.[65]