Basically, they are immortal tissues. If you remove a tube foot or two from a scarlet sea cucumber and leave the tube feet in regular, bacteria-infested seawater, they will heal themselves and just carry on absorbing nutrients and staying alive as a detached foot for YEARS. YEARS!!!!
My incredible friend Sara has published a WILD paper from her soon-to-be-completed PhD, which is about IMMORTAL SEA CUCUMBER BITS www.science.org/doi/10.1126/...
Sara had just started her PhD and this specific experiment when I started my Masters in the same lab, and I vividly remember walking into the lab my first week there and seeing a notebook ominously placed in the centre of the table that just said "zombie project"
I didn't know what Lorenzen Mushrooms were before but now I'm obsessed with them
I love prehistoric giant bugs and I love dioramas
I finally visited Joggins, Nova Scotia, and met the man*, the myth, the legend: Arthropleura trackways!!!
*giant Carboniferous millipede
(Left image from Emaline Montgomery, right is from the paper)