[See]

[Sex] "Asexual reproduction is easier than sexual reproduction, but there are benefits and drawbacks to both..."

[Book Review for "Life: A Natural History of the First Four Billion Years of Life on Earth" by Richard Fortey] "Sexual reproduction, which first appeared about a billion years ago, accelerated the pace of evolution. Previously, changes in species arose mainly through mutation, a process that was relatively infrequent, quite haphazard and often destructive rather than beneficial. Sexual reproduction allowed offspring to inherit the features from their parents, thereby allowing change through combination."

[Do snails have eyes?] "Snails have very poor vision. Even though they have a lens on their eye, they have no muscles to focus the images. They can sense light and dark and work out where the light source is."