Eos 5d

The morphology and corresponding elemental mapping images of MME structures were measured using scanning electron microscopy (Quanta 400 F, FEI, USA) and its energy dispersive spectroscopy (EDS), respectively. NdFeB microparticles and liquid metal distribution inside the MME structure were measured by micro-CT (GE Vtomex). The optical photos of the MME structure were captured by the digital SLR camera (EOS5D, Canon, Japan). The morphology of the MME structure was measured by the ultra-depth three-dimensional microscope (VHX-7000, KEYENCE, Japan).

The surface topography of dual-layer magnetic paper was observed using an industrial digital camera (CM2000, KUY NICE, China). The magnetic flux density of magneto-origami was measured by a gauss meter (Shanghai Daxue Electromagnetic Equipment Co., Ltd., China). The contractions strain and folding angle of magneto-origami actuators were characterized by analyzing the Supplementary Movies recorded by a digital camera (EOS 5D, Canon, Japan) using Image J. The magnetic hysteresis loop of bilayer matter was obtained using a vibrating sample magnetometer (VSM, Lake Shore 7410, USA).

Five specimens of Astrodia were collected by ROV HAILONG III, ROV HAILONG IV, and HOV JIAOLONG, from seamounts in the Philippine Sea and the Northwest Pacific, during several COMRA’s cruises in 2013, 2020, and 2021 (Fig. 1). All specimens were preserved in 95% ethanol on board the vessels and photographed using a digital camera (Canon EOS 5D), then deposited in the repository of the Second Institute of Oceanography, Hangzhou, China (RSIO).

Photos of early embryos were taken with a Zeiss Lumar V12 fluorescence stereomicroscope equipped with NA objective (ApoLumar S1.2X) and AxioCam MRm camera. Images were taken using Zeiss AxioVision 4.8.2 software. The contrast of the TIFF images was adjusted with Adobe Photoshop. Photos of adult flies, larva, and pupa were taken with a Zeiss Stemi SV11 stereomicroscope equipped with NA objective (S 1.0X) and Canon EOS 5D camera (attached to the binocular the tube via Gosky T2 camera mount; 23.2 mm eyepiece port). The contrast of raw images was adjusted with Adobe Photoshop. The size standard was photographed separately in the same condition and the image was merged with Photoshop. No filters are used for any photos. Standard light (halogen gooseneck lamp) was used for both microscopes.

A fine scale ROV survey, covering the area mapped by the multibeam (Fig 2), was carried out to classify and characterize the hydrothermal structures and the associated fauna. The Pollux III ROV was equipped with a high resolution camera (Canon EOS 5D, 20 megapixel), two strobes (Canon), a high definition video camera (Sony HDR-HC7), 3 jaw grabbers, two parallel laser pointers to measure in situ seafloor structures and a USBL (Ultra Short Baseline—TrackLink 1500 MA Link Quest Inc.) underwater acoustic position system to accurately record the ROV’s geographic position. The main hydrothermal structures were identified and mapped. A small basket net was installed on the ROV to collect samples of terminal parts of chimneys. Samples of a total of three chimneys were collected, named VA (Chimney_VAlentina, 38°39’27”N, 15°6’1”E), SF (Chimney_Sagrada Familia, 38°39’25”N, 15°6’0”E), and GB (Chimney_Giovanni Bortoluzzi, 38°39’23”N, 15°5’57”E) (Fig 3B). In addition, a fourth chimney (RC, Chimney_ReConstructed, 38°39’30”N, 15°6’3”E) (Fig 3B) was reconstructed by means of a mosaic of 250 HD-video images processed with the Software Agisoft PhotoScan (www.agisoft.com) in order to provide a graphical representation of the investigated chimneys allowing a better understanding of the size and shape of the entire structure of the chimney.