Two more nuclear tests were conducted in the Monte Bello Islands as part of Operation Mosaic in 1956, the detonations taking place on Alpha and Trimouille Islands. By the 1980s the radioactivity had decayed to the point where it was no longer hazardous to the casual visitor, but there were still radioactive metal fragments containing cobalt-60, the remains of "Plym". The island remained a prohibited area until 1992. A 2006 zoological survey found that the wildlife had recovered, and that the "Aprasia rostrata", the legless lizard discovered by Hill, was not extinct. As part of the Gorgon gas project, rats and feral cats were eradicated from the Monte Bello Islands in 2009, and birds and marsupials were transplanted from nearby Barrow Island to Hermite Island. Today, the Monte Bello Islands are a park. Visitors are advised not to spend more than an hour per day at the test sites, or to take relics of the tests as souvenirs. A pyramid-shaped obelisk marks the site of the explosion on Alpha Island.