A mysterious floating orb, a giant inflatable mushroom cap and a cube whose walls are curtains of water — those were the inventive if improbable top picks in the international competition to devise an eye-popping new stage for the long-shuttered Miami Marine Stadium.

The fanciful designs, chosen by a high-profile jury, were meant to excite public imagination over the possibilities of a restored marine stadium. The deteriorated, graffiti-scarred, raw-concrete structure on Virginia Key, closed since 1992, is increasingly regarded as one of Miami’s signature masterpieces of modern architecture and engineering.

“These are only ideas to fire the imagination and return Miami Marine Stadium to a wonderful new life,’’ Frank Sanchis, a jury member and head of U.S. programs for the World Monuments Fund, told a packed house at the award presentation Monday evening at the Rusty Pelican restaurant next door to the stadium.

Or, as juror and artist Michele Oka Doner put it: To find Miami’s “sleeping beauty’’ her prince.

To be sure, the striking 1963 landmark by architect Hilario Candela, once the beloved site of concerts, powerboat races and Easter sunrise services, today more closely resembles a frog. Closed by the city of Miami after Hurricane Andrew and once slated for destruction, the folding planes of the stadium’s thin-shell concrete roof and its grandstand built over the water have been badly degraded by climate and vandals. The converted oil barge that served as the floating stage on which stars from Elvis Presley to Jimmy Buffett performed is half-sunk in the stadium’s artificial basin.

But concerted efforts by preservationists, architects and marine-stadium fans, grouped as Friends of Miami Marine Stadium, succeeded in winning legal protection as a historical landmark from the city while rallying international support for its restoration. Costs are expected to run into the millions of dollars, only some of which has been raised.

Thus the competition, co-sponsored by the Miami chapter of the American Institute of Architects and the National Trust for Historic Preservation and run by DawnTown, the upstart group that has run re-design contests for the downtown Miami sewage pump station and the closed Bicentennial Park Metromover station.

Meant to keep the stadium cause in the global public eye, DawnTown’s floating-stage competition appears to have succeeded, drawing more than 80 entries from around the world. To up the ante, the floating stage was required to be fully navigational, so it could be floated to other sites around Biscayne Bay, including Vizcaya and Bayfront Park.

In the end, after long discussion, the jurors chose a winner from a place not known as a hotbed of design: Lincoln, Neb. The team of Jiong Wu and Gengxin Ou of Abingo Wu Studio won $5,000 for Miami Pearl, a glowing, ethereal-looking floating sphere that would contain a stage and was praised by jurors for its “gorgeous design.’’

A close second was Inflatable, by Eric Tan and Leon Lai of Pink Cloud.DK.Design Group in Copenhagen, Denmark. A large, helium-inflated disc roughly shaped like a mushroom cap and punctured by holes for natural lighting would serve as a canopy over a stage made of easily assembled and transportable components.

Finally, in the first local entry to break into the top three of a Dawntown competition, Igor Reyes of Coral Gables took third for The Waterbox. The floating cube would have walls made of illuminated, cascading water.