Quagmire

Quagmire is a kind of dangerous mud likely to never release whoever falls into it. The block uses the mechanics of spider webs while still being solid like a block, thus making you suffocate when you sink in. This block can be found in biomes with a lot of water (e.g. Dead Marshes, Midgewater, etc.), and is usually located near the water sources. It is possible to break the blocks with a shovel. In fact, this is currently the only and fastest way of escaping the quagmire.