Heart of darkness they were discoloured just awash and the whole lot was seen just under the water exactly as a mans backbone is seen running down the middle of his back under the skin

Personafication

Explanation: Personafication means referring to or giving non living things the qualities of human or living things. "Heart of darkness they were discoloured", the heart is part of the human body but in this context it is given the human attribute where "they" pronoun is referred to the heart. Also "backbone is seen running down the middle of his back", backbone is just part of the human body but in this context it it made to run down like it ia literally running down onea back.

in other words

to put it differently

for one thing

as an illustration

in this case

for this reason

to put it another way

that is to say

with attention to

by all means

important to realize

another key point

first thing to remember

most compelling evidence

must be remembered

point often overlooked

to point out

on the positive side

on the negative side

with this in mind

notably

including

like

to be sure

namely

chiefly

truly

indeed

certainly

surely

markedly

such as

especially

explicitly

specifically

expressly

surprisingly

frequently

significantly

particularly

in fact

in general

in particular

in detail

for example

for instance

to demonstrate

to emphasize

to repeat

to clarify

to explain

to enumerate