Actually, in a spherical container. Samples from Mars have always been desired by scientists here on Earth but there were several problems. One, getting it back here, two cross contamination, and three re-entry into Earth’s atmosphere & NOT relying on a parachute.
While positive that there will be science fictions written of the container from Mars, the container pictured has been specially engineered to keep such samples safe. Such a mission, a sample-return mission, is probably years away, plus the time to make such a rover and the time to send it, so we’re talking a good amount of time. BUT we have created the first part, a necessary part for that eventuality.
Before being returned to Earth, this container which weighs less than 5 kg (carry-on luggage fee?) must go along for the trip to Mars then being loaded with samples by its robotic predecessor or companion, depending on the manner selected to complete this mission. Second, the container must be sealed. The one pictured features 11 sealable receptacles – one on the seals is for a sample of Martian Air. Finally it will be sealed into another bio-sealed vessel to ensure containment.
Once the container has its samples and is deemed safely loaded with cargo, it will be launched up into the Mars Orbit. From there is will rendezvous with another spacecraft. For this reason the sample container carries a radio emitter and retro-reflectors for laser ranging.
After the lengthy trip back to Earth is complete there are a number of problems that are being considered due to the strict planetary protocols when bringing potential contaminants from space into contact with Earth.
The portion of such a journey that brings concern is the landing. Obviously some sort of heatshield will be required to keep the specimens intact but additionally simply parachuting to a safe landing is not exactly secure. There are too many what-ifs. The container must be able to survive the fall to earth without a parachute. The mission design at present is to avoid any plan that would require a parachute and instead have the deceleration occur as a direct result of the pressure on the heatshield during re-entry and the eventual impact at landing.
While I couldn’t locate any exact choices, I would opt for that beach ball type design used by the Mars Rover.