Benthic Explorers

The mana ability does something almost no card before or since attempts: it siphons mana out of an opponent's already-tapped lands by untapping them, which means the resource you steal is the resource they just spent. The friction built into that design is real and double-edged. You need a tapped land to target, so the ability only fires after an opponent has committed mana; and untapping their land hands it straight back to them, giving them extra mana in the current turn cycle that they would not otherwise have had until their own untap step. What you are buying, in effect, is a one-shot mana boost timed to their tempo rather than yours, paid for by handing them an unscheduled untap. The 2/4 body is the giveaway that Alliances treated this as a utility creature rather than a threat: it survives long enough to keep tapping. The deeper appeal was always color-fixing through theft, producing whatever exotic mana the opponent's nonbasics could make, which in a multicolor environment turned an opponent's dual lands into your own. It is a Johnny card in the truest sense, a puzzle piece looking for a board state weird enough to reward it, and that puzzle-box quality is exactly why it never found a fair-deck home and exactly why it keeps getting rediscovered.