The 26-year-old lineman was removed from the field for lack of condition. Coach John Harbaugh talked with Pierce after the stretching portion of practice, and the defensive tackle left the field.
"He's not ready to practice from a safety standpoint and for his own health," Harbaugh said, via ESPN. "We recognize that and pulled him off."
Pierce, a restricted free agent, didn't attend previous voluntary offseason workouts. He is set to make a non-guaranteed base salary of $3.095 million in 2019. He'll be a free agent in 2020.
According to ESPN's Jamison Hensley, the defensive tackle looked heavier than his listed playing weight of 340 pounds.
"He's not ready for this practice yet," Harbaugh said. "I think you could probably tell."
An undrafted free agent signing in 2016, Pierce impressed through his first three seasons. As a rotational player, Pierce earned the fifth-highest grade for an interior defender from Pro Football Focus and was the fourth-best against the run.
If he doesn't get on the practice field this week, the next chance is during training camp in late July.