Bridge Seed

When thrown, this illusion seed turns into a wooden bridge with stone piers, covering a stream, moat, chasm, gorge, or river up to 40 feet across. If thrown into a space where a creature is standing or swimming, that creature finds itself standing on the bridge decking without suffering any ill effect. The bridge can be undermined by flooding or burnt by fire normally. Otherwise, it remains standing for decades, slowing decaying.