Here is the passage:
Marina, the beautiful mermaid, wanted some
tuna salad. But had a small problem since she was allergic to celery. At
Sammy’s Sub Shop, Marina hoped to find tuna salad free of this dangerous
vegetable. Flopping across the tiled floor to the counter. Marina placed
her order and then checked her sandwich for celery.
Not noticing, however, the spoiled mayonnaise.
At five o'clock that evening, Marina became violently ill with food
poisoning. When a lifeguard at the beach discovered the problem, he called
911. Even though the mermaid had fishy breath. A handsome paramedic gave
her mouth-to-mouth resuscitation. Wailing like a sick dog, the ambulance
sped off to the hospital. Where the doctor on call refused to treat a sea
creature with a scaly tail. A kind nurse, however, had more sympathy. When
this caregiver returned with a liquid antacid. Marina drank the entire bottle,
feeling an immediate improvement. The mermaid told the rude doctor never
to swim in the ocean. For she would order hungry sharks to bite off the
doctor's legs. While sharp-clawed crabs plucked out his eyes. Tossing
her long hair, Marina thanked the nurse for the antacid. And took a
mint from David, the handsome paramedic.
Good job! A fragment will not have a main clause. A main clause follows this pattern:
Subject + Verb = Complete Thought.
In the highlighted item, noticing is the word expressing action. The ing that ends it, however, makes noticing a participle, not a verb. Without a verb, you cannot have a main clause.
All you have here is a participle phrase fragment.