Ea R'lyeh Aboleths.

[HoneyBadger]

Since the mech idea doesn't seem to be going down all that digestably for some, maybe instead spawn could simply be attached to living creatures, magically? They might combine with sea trolls, giant crabs, mantas, etc., dissolving their will with direct psychic enslavement, while the bodies of the aboleth spawn themselves grow into the hosts, creating a new and far more horrifying being.