Biologist Jon Allen is the proud owner of the world's oldest ribbon worm on record.

The adopted invertebrate is fondly called Baseodiscus the Eldest, and he is at least 26 years old, probably around 30, according to a new analysis.

When fully stretched out, Baseodiscus, or 'B' for short, is roughly a meter (3 feet) long, but its age has been harder to pin down.

Related: The Stem Cell Secrets of This Tiny Worm Could Help Unlock Human Regeneration

Marine invertebrates are some of the longest-lived animals on the planet, and deep-sea tube worms can live for 300 years or possibly more .

Ribbon worms are particularly ubiquitous marine invertebrates, yet we know little of their lifespans.

B is the oldest recorded creature in the phylum Nemertea by a long shot. The only other cont

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