Do complex sentences always need a conjunction? [closed]

"At her age, Minggay Awok's only companions were a few charcoal black chickens."

Because of "At her age," does this make the sentence complex, or is it still a simple sentence? I do know complex sentences are supposed to have conjunctions, but this phrase clearly cannot stand on its own.

A complex sentence has more than one clause, and a clause requires a subject and verb. "At her age" is a prepositional phrase, which doesn't contain a verb, so your sentence remains simple.

Conjunctions may be omitted. Punctuation may take their place:

Minggay Awok was lonely; her only companions were a few charcoal black chickens.

His business judgment was soon proved correct: the company went bankrupt three months later.

Or a conjunction may be [elided]

She's the one [that] I've always loved.

I believe complex sentences don't always need a conjunction. For example, the sentence which precedes this one is conjunctionless yet complex.