Stygiomedusa gigantea, commonly known as the giant phantom jelly is a part of the monotypic genus of deep sea jellyfish, Stygiomedusa. This is in the Ulmaridae family. It can't actually sting you as its—30-foot-long—”mouth arms” are just there to trap prey rather than sting them.
This ghostly giant is a rare sight.
MBARI's ROVs have logged thousands of dives, yet we have only seen this spectacular species nine times. The first specimen of the giant phantom jelly was collected in 1899, but it was not until 60 years later that scientists recognized this as a new species.
Chinese giant salamander (娃娃鱼) a.k.a ‘baby fish’ due to the sound they make that sounds like a baby crying.
The Chinese giant salamander is one of the largest salamanders and one of the largest amphibians in the world. It is fully aquatic and is endemic to rocky mountain streams and lakes in the Yangtze river basin of central China.
The Chinese giant salamander is considered to be a "living fossil". Although protected under Chinese laws, its population has faced severe declined over the last 70 years and is currently (2022) listed as threatened. There are evidence indicating that the Chinese giant salamander may be composed of at least five cryptic species, further compounding each individual species' endangerment. It can reach up to 50 kg (110 lb) in weight and 1.8 m (5.9 ft) in length.
Here is a video of a 200-year-old Chinese giant salamander that was found in a cave.