it is water mammals
"Watermammals" is one word.
It is two words. Writing it as one is acceptable in the UK and is referred to as a "Britishism." But in American grammar, it is always two separate words.
Two words - "one day".
"After school" is typically written as two words.
"Pogostick" is typically written as one word.
They are two words conjoined to be one.
"Good day" is generally considered to be two words.
It is two words take it from a 7th grader
I recommend class work, as two words.
It is two words.
Two words.
It's two words. :)
It is two separate words.