In fantasy worlds, trees like the Lord of the Rings’ Ents are agile and mobile. In the real world, they’re slow.

Strange cone-shaped rocks led scientists to the hidden remains of one of Earth’s oldest asteroid impacts. It could help us find fossil life on Mars.

New versions of the H5N1 virus are increasingly adept at spreading. Suggestions to either let it rip in poultry or vaccinate the birds could backfire.

For the first time, scientists have 3-D printed objects within living cells, including a 10-micrometer long elephant and tiny “barcodes” that could help track individual cells. Remarkably, many of the ...