Sea urchins in my pit?

[Zshields]

Id like to start by saying im semi new to the car wash industry- today my site staff were assigned to clean the pit in the tunnel after we close, my coworkers have said that they have seen sea urchins in the mud that we have scooped out, i just dont find this believable at all, and wanted to ask is this truly possible?

 

[Islandwash]

I doubt it, but after 30 years I admit that I try hard not look at the pit mud .and avoid it.