if I might add:
transports able to pick up enemy units, then the unit stops firing whatsoever like as though it doesn't know it's on an enemy transport.
this should either -require- the unit be emped before picking up, (as then it's actually disabled, not just standing still) or it takes damage when doing so (enemy unit fighting back).
urchins can be built on land.
1: it makes a torpedo launcher untargettable by torpedo launchers. this doesn't even make sense as torpedos would need to be -in- water to fire.
2: gameplay wise it's broke as well, as this makes urchins completely invincible to all but maybe 2 sea units, including ones that are obviously -supposed- to be a hard counter to them (sniper submarines)
in short, it makes the urchins -completely- overpowered compared to the rest of the sea units available.
-edit: or an even simpler solution... torpedoes launch themselves into the air to hit it, but will very quickly fall back to the ground making there range onto ground -extremely- limited (the same amount it takes an urchins torpedo to fall)