Female Sea Snails No Longer Growing Penises Thanks to Ban on Toxic Chemical

Whelks like these were growing both male and female genitalia after being exposed to toxic TBT. Ships in the 1960s were often coated in a chemical called TBT to prevent sea critters like snails from clinging to the hull. After researchers found that the toxic chemical caused female sea snails to grow penises (alongside equally frightening effects in other species) the stuff was banned in 2008. Now, six years later, things are starting to look up for the snails.