Oh the muttering in Paleobiology staff at the Smithsonian. Apparently a notation on the Tower of Time in the Museum of Natural History mistakenly references the Precambrian era. And yet the notation has remained since the tower was placed in 1981.
But, a fifth grader noticed the issue and brought it to the attention of museum staff. Kenton Stufflebeam got a letter back from the museum, indicating that he was correct and that they would likely remove the word era from the tower. Sadly, the letter spelled his name wrong.
PS - Thanks to the friend who passed this story on to me.