Jack Conway was a science teacher, specializing in pre-history. He did a PowerPoint presentation on the abrupt appearance of new species at the beginning of the Cambrian, 543 million years ago, noting that this sudden appearance was unexplained, but that interesting theories abounded. Spoiler warning: Plot and/or ending details follow. The actual reason for the sudden appearance of life in the Cambrian period was due to a family of intergalactic travelers that arrived on pre-historic Earth and released their aquatic pets into the planet's environment.