Manis Mastodon Site, Archaeological site in Clallam County, United States.

The Manis Mastodon Site is a 2-acre archaeological site in a former peat bog in Happy Valley, south of Sequim, Washington. A grey stone marker with a recessed panel and the carved inscription "MANIS MASTODON SITE" stands on a stepped base in the grass, with hills beyond. The excavated remains include a mastodon rib holding a bone projectile point.

In August 1977 Emanuel "Manny" Manis found two mastodon tusks while digging a dry peat bog on his Happy Valley property with a backhoe. Excavations led by Carl Gustafson of Washington State University recovered a rib with a bone projectile point embedded in it, dated to about 13,800 years ago. The site joined the National Register of Historic Places in 1978, and in 2002 Manis's widow donated it to The Archaeological Conservancy.

The site is on private land managed by The Archaeological Conservancy and is not open for visits, so the finds are seen at the Sequim Museum & Arts, where the mastodon fossils and a cast of the bone point are displayed. Shirley Manis, daughter of the discoverer, wrote a children's picture book about the site in 2011.

The 2-acre site in Happy Valley, south of Sequim, is not open to the public. The excavated mastodon remains and a casting of the bone projectile point are on display at the Sequim Museum & Arts in Sequim, where visitors can see them.

Scientists found bone growth around the embedded spear point, showing the mastodon survived the initial hunting attempt. This healing response offers rare insight into how animal and human interacted in that distant time.