Seaweed Cultivator

Whenever you remove two or more travel
counters from Seaweed Cultivator, return it to
the battlefield under your control. When you do,
add {g}{g}. Until end of turn, you don't lose this
mana as steps and phases end.
{t} : Seaweed Cultivator travels. (Exile this card
with a travel counter on it. At the beginning of your
upkeep, put a travel counter on it or remove all travel counters from it.)