Boca Ciega, Florida -- A chemistry project caused a big problem at Pinellas' Seminole High School Tuesday morning.
The Pinellas County Sheriff's Office says students were given an assignment to bring in a substance from the Periodic Table of Elements.
One student brought in mercury -- contained within a thermometer -- and the school went into lockdown.
Deputies say the thermometer was discovered as the substances were checked before going through the school.
No one was put in harm's way, but a hazmat crew was there as a precaution.
Pinellas County Schools tell 10 News the students were told not to bring certain toxic elements from the periodic table, mercury included.
You May Also Like...
Bikini Photos: 2012 Hooters International Swimsuit Pageant
Caught on Camera: Dashcam catches 14 illegal immigrants jumping from SUV
Really?!?: Dashcam catches man urinating on patrol car
Gah: Nose ring found in McDonalds burrito
7-11 Nudie: Nude robber boosts 7-11, video
Lil Girl Gang: Little girls busted in burglary ring
Oh Deer: Video catches deer tangled in Christmas lights
Sex Offender Search: Look up Florida Sex Offenders here
Lawsuit: Scientology allegedly covered up woman's death
Lovely Angels: 2012 Victoria's Secret Fashion Show pictures
Yowtch! Teen accidentally shoots off his penis, testicle
Cheerleader sex: Former Ben-Gal pleads guilty to sex with teen
Unwelcome house guests: Coyotes move into abandoned mansion
PHOTOS: George Zimmerman/Trayvon Martin crime scene pics
Not just a game? Man murdered for Magic: The Gathering cards
Yearbook mug shot: Teen who posed in racy yearbook photos busted for underage drinking
Bikinis, mud, trucks: The Redneck Yacht Club
Photos: Ex-Charlie Sheen Goddess Bree Olson
Naughty Schoolgirls: Naughty schoolgirl night at Tampa club pictures
Outrageous mug shot galleries...
Strange: Some of the most unusual mug shots we've seen
Notorious Women: Bad girls behind bars
Teachers: Teacher arrest mugshots
Celebrities: The rich and famous have their own booking photos
Jaw droppers: Open mouth mug shots
Laughers: What's so funny mug shots
Prostitutes: Prostitute mug shots
Athletes: Professional athlete mug shots
Porn arrests: Child porn arrest mug shots
Local Mugs: Hillsborough County Mug shots
More unusual mug shots and galleries: 10 News slideshows and galleries