Imagine that you're coral at the bottom of the sea — a thrilling fantasy, we know. You're minding your own coral business when suddenly some obnoxious scuba diver ungraciously dumps sediment on you. How do you free yourself from this sand trap?
If you happen to be mushroom coral, you can extricate yourself by inflating and deflating over a period of 10-20 hours. This occurs at a painfully slow rate in real time. But when condensed into less than two minutes, this process is a National Geographic documentary directed by David Cronenberg. The University of Queensland made these incredible time-lapse videos — here's what you're seeing:
Although many coral species exhibit the capacity of active sediment rejection, only few are capable of freeing themselves after becoming completely buried. Fungiid corals appear to be an exception, as they can remove sediments through substantial polyp inflation (up to five times their normal size) in addition to mucus entanglement and ciliary action [...] The combination of rhythmic pulses and peristaltic waves (during deflation) appears to represent an effective sediment shedding mechanism that allows these fungiids to excavate themselves within hours.
I'm sure there's a Cthulhu joke in here somewhere, but we did that song and dance earlier today.