Tetzcotal Sea Terror
Is this an egg or a creature? You dare not prod at it to find out if it has a hard exterior; what if it stings you? It certainly reacts to its environment, but moves in a solely instinctual fashion to stay in water of the correct temperature. Aha, now you see the shell. It's an egg.
Male/Female Hatchlings (No Dimorphism), changes form
Spoiler
This formidable young Tetzcotal sea terror already has lengthy periods of fierce and menacing behavior, patrolling the area for foes. A hatchling is poisonous rather than venomous, and in the wild many are killed by predators who have no intention of eating them: the hatchlings are, rather, killed as one might eliminate a potential rival in a weak moment. A wild hatchling is far more wary and fierce, but the companion of a magi relaxes in trust and is easily distracted by the flash of a coin tossed in the water, and will happily play with the offering for hours before remembering to practice guardianship skills.
Male/Female Adults (No Dimorphism), changes form
Spoiler
By the time they reach adulthood, the predatory instincts of the Tetzcotal sea terror are well developed; but so is a complex sense of play. They have been noted to devote weeks to establishing some quirk of routine, seemingly for the sole purpose of using an established assumption as basis for jokes of a sort. Not that a magi splashed with chilly seawater always appreciates the joke. Magi have further noted that they do not eat terribly often when in a higher magic environment, and it is believed that in some way they consume magical energies as part of their routine diet. There has been talk of using them to map out energy currents just as other ocean creatures can help a magi map out water currents.
Spoiler
These deadly predators found in the ocean near Tetzcotal are a rare sighting; perhaps once a year their migratory habits bring them close enough to the coast that fishermen will find them tangled in nets. Typically such nets are cut and written off as a loss, as most are loathe to risk getting too close to such deadly, though beautiful, creatures. They are a fairly deep water animal, with the ability, perhaps magically augmented, to phosphoresce a beautiful bright blue which is stark contrast to their typical darker patterning. Magi have only recently discovered them, and are still studying whether this is hunting or mating behavior, or possibly something else altogether. When bonded with a magi, they stay in shallower waters or aquariums close to hand, and typically only display their phosphorescence at night.
