Join Dr. Mark Edlund, senior scientist at the Science Museum of Minnesota's St. Croix Watershed Research Station, from 2 to 3 p.m. on Saturday, April 29, at Hardwood Creek Library to learn about tiny one-celled life forms called diatoms. Diatoms are one of the most important things you never knew about! Discover the tiny one-celled life forms that live in every drop of water during this engaging program. Thanks to Dr. Mark Edlund for his time and the Science Museum of Minnesota for the loan of microscopes.  Grades 3 and up.