LONDON -- Brace yourselves for this one -- it isn't for the faint-hearted.

On Thursday evening,Watch Human Capital Online BBC Earth tweeted the following, slightly unexpected gif.

This Tweet is currently unavailable. It might be loading or has been removed.

Yep, that is a pearlfish worming its way up the rear-end of a sea cucumber. Just think about that for a moment. The pearlfish actually scouts the ocean looking for sea cucumbers with the express purpose of cheerfully burrowing its way into their anal cavity for protection.

Needless to say, BBC Earth's tweet drummed up some mixed reactions.

This Tweet is currently unavailable. It might be loading or has been removed.

Some people were appalled.

This Tweet is currently unavailable. It might be loading or has been removed.

This Tweet is currently unavailable. It might be loading or has been removed.

This Tweet is currently unavailable. It might be loading or has been removed.

Others, meanwhile, were clearly torn between shock and intrigue.

This Tweet is currently unavailable. It might be loading or has been removed.

This Tweet is currently unavailable. It might be loading or has been removed.

Others were impressed with the BBC's choice of hashtag.

This Tweet is currently unavailable. It might be loading or has been removed.

This Tweet is currently unavailable. It might be loading or has been removed.

If you can stomach it, here's a longer video about the adventures of the pearl fish.

Have something to add to this story? Share it in the comments.